renovate: align the config with cluster-config

The shared jlab-renovate-bot instance serves this repo and cluster-config,
and two repos behaving differently under one bot is a source of surprises
rather than of safety. This adopts cluster-config's configuration:
config:best-practices in extends, labels ["renovate"], no PR caps
(prHourlyLimit 0, prConcurrentLimit 100), separateMinorPatch, an explicit
dependencyDashboard, and global automerge with platformAutomerge.

Two of those choices were previously wrong here and are now right, because
the branch protection on main has caught up: a review requirement and
validate-charts as a required check are both active. platformAutomerge
therefore arms the PR on the forge and Gitea merges it when the check
passes AND the review exists - the review is the gate, which is what makes
automerging majors something other than unattended merging.

Comments that asserted the opposite are rewritten rather than left to rot:
the platformAutomerge: false comment ("not (yet) a required check on either
side"), the "Majors stay manual" rule, the README PR policy bullets and the
required-check paragraph, and the CLAUDE.md forge notes.

config:best-practices pulls in docker:pinDigests, which is switched off
again for custom.regex and helm-values: an appVersion: is a tag by
construction and has nowhere to put a digest. Kept deliberately:
minimumReleaseAge of three days on the routine updates (every merge here
publishes a chart), the ignorePaths and ci/** opt-outs, every per-chart
manager, the nginx and qbittorrent constraints, and postUpgradeTasks.

Fixes #34

README.md

@@ -67,7 +67,7 @@ Everything below was measured on this instance, not taken from documentation, an
 
 **Runner labels mean different machines than on GitHub.** `ubuntu-latest` here has **no Docker socket**; `ubuntu-docker` has one. Exactly one job cares — the install-test, because k3d is a Docker client — and its `runs-on` is therefore an expression rather than a fixed label, so the same file still works on a GitHub runner where `ubuntu-docker` does not exist. Every other job (lint/package, the quantity render, the Trivy scan) needs no socket and stays on `ubuntu-latest`.
 
-**A matrix runs concurrently inside ONE job, under ONE status context.** This is the single most consequential difference and it has two halves. Operationally: all legs share one Docker daemon, which is what makes a per-leg resource name mandatory (see the cluster name below). For branch protection: **a required check per chart is not possible**, because there is only one context for the whole matrix — and its name carries the *unexpanded* matrix expression, e.g. `Validate Helm Charts / Install-test ${{ fromJSON(needs.detect-changed-charts.outputs.install-charts) }} (pull_request)`. Required-check names have to be read off a real run; they cannot be copied from GitHub.
+**A matrix runs concurrently inside ONE job, under ONE status context.** This is the single most consequential difference and it has two halves. Operationally: all legs share one Docker daemon, which is what makes a per-leg resource name mandatory (see the cluster name below). For branch protection: **a required check per chart is not possible**, because there is only one context for the whole matrix — and its name carries the *unexpanded* matrix expression, e.g. `Validate Helm Charts / Install-test ${{ fromJSON(needs.detect-changed-charts.outputs.install-charts) }} (pull_request)`. Required-check names have to be read off a real run; they cannot be copied from GitHub. What *is* required on `main` today is **`validate-charts`**, as the single context it reports under, alongside a **review**: per chart is the part that is impossible, not required checks as such. Both are what makes Renovate's `platformAutomerge: true` safe — see "PR policy".
 
 **Expected runtimes**, so that a later deviation is visible as one:
 
@@ -159,7 +159,7 @@ What Renovate keeps current:
 
 Each chart renders its main image as `<repo>:{{ .Chart.AppVersion }}` — repository in the template, version in `Chart.yaml`. Renovate cannot join two files, so the mapping lives in `renovate.json5`, one block per chart. It is deliberately *not* a `# renovate:` comment inside each `Chart.yaml`: that would touch all chart directories and force a version bump plus a publish per chart for a pure comment change. Charts whose tags carry a flavour or date suffix (`apache-tika`, `minecraft-server`, `rss-bridge`, `searxng`, `teamspeak-server`) override `versioning` in their block; the reasoning sits next to each one.
 
-One rule those overrides share, learned from `searxng` and worth knowing before writing the next one: **a capture group is a claim about how the value is compared.** Renovate's regex versioning parses `major`, `minor`, `patch`, `build` and `revision` with `Number.parseInt` (`modules/versioning/regex/index.js`, `_parse`), so a non-numeric commit hash captured as `build` becomes whatever digits lead it — `9fea41204` is `9`, `777ba8fa4` is `777`, and a hash starting with a letter is `NaN`. Measured on renovate 41.173.1 and 44.48.0, that makes Renovate offer an image pushed *earlier the same day* as an update to a newer one, unattended under the patch/minor automerge rule. Parts of a tag that carry no ordering belong **outside** every group: the anchored pattern still requires them to be there, they simply take no part in the comparison. `prerelease` is not the way out either — it sorts correctly but marks every tag `isStable === false`, which hands the whole chart to `ignoreUnstable`. `freesailarr` has no **app-version** block on purpose — see the images exception above; a block would either duplicate the `helm-values` updates or rewrite an `appVersion` that selects no image. It does carry one `customManagers` block, for `mediathekarr`: that image is pinned by digest because its tags carry no version (`latest` is a 2024 build, `beta` moves), and the built-in `helm-values` manager reads only `repository`/`tag` and skips it (`skipReason: invalid-value`), so the two cannot collide. Digest rules need the same guard as versioning rules and for a sharper reason: while the pin is current, a matching rule and a broken one produce the identical empty result. Verified with two dry-run fixtures — the real digest yields no update, a deliberately stale one yields exactly one `digest` update back to the pinned digest.
+One rule those overrides share, learned from `searxng` and worth knowing before writing the next one: **a capture group is a claim about how the value is compared.** Renovate's regex versioning parses `major`, `minor`, `patch`, `build` and `revision` with `Number.parseInt` (`modules/versioning/regex/index.js`, `_parse`), so a non-numeric commit hash captured as `build` becomes whatever digits lead it — `9fea41204` is `9`, `777ba8fa4` is `777`, and a hash starting with a letter is `NaN`. Measured on renovate 41.173.1 and 44.48.0, that makes Renovate offer an image pushed *earlier the same day* as an update to a newer one — a downgrade wearing the clothes of a routine date bump, which is exactly what a review waves through and automerge then carries to `main`. Parts of a tag that carry no ordering belong **outside** every group: the anchored pattern still requires them to be there, they simply take no part in the comparison. `prerelease` is not the way out either — it sorts correctly but marks every tag `isStable === false`, which hands the whole chart to `ignoreUnstable`. `freesailarr` has no **app-version** block on purpose — see the images exception above; a block would either duplicate the `helm-values` updates or rewrite an `appVersion` that selects no image. It does carry one `customManagers` block, for `mediathekarr`: that image is pinned by digest because its tags carry no version (`latest` is a 2024 build, `beta` moves), and the built-in `helm-values` manager reads only `repository`/`tag` and skips it (`skipReason: invalid-value`), so the two cannot collide. Digest rules need the same guard as versioning rules and for a sharper reason: while the pin is current, a matching rule and a broken one produce the identical empty result. Verified with two dry-run fixtures — the real digest yields no update, a deliberately stale one yields exactly one `digest` update back to the pinned digest.
 
 A consequence of pinning every tag in `values.yaml`: `ci/renovate-bump-chart.sh` sees an unchanged `appVersion` and bumps the chart **patch**. That holds for all ten images alike, the digest-pinned one included — none of them is special — and it is the intended outcome, since `appVersion` here is the chart's own marker rather than a tracked upstream version.
 
@@ -202,9 +202,13 @@ One item is easy to miss and is named in "The version-bump hook" above: the inst
 
 ### PR policy
 
-- **Automerge** for `patch`, `minor` and `digest` updates, after a `minimumReleaseAge` of 3 days and only once the PR pipeline is green — install-test included, which is why that job no longer runs with `continue-on-error`. Minor is in scope because the sidecar images barely move in patch steps (`alpine 3.22` → `3.24`, `nginx 1.30.4` → `1.31.4` are both minor), so a patch-only rule would practically never fire. Renovate merges itself (`platformAutomerge: false`) rather than handing the PR to the forge's own auto-merge, which on **both** GitHub and Gitea would merge immediately as long as `main` has no required status checks. That is a statement about the branch protection, not about the platform: once required checks exist on `main`, `platformAutomerge: true` becomes the better setting on either side. Majors are merged by hand.
-- **Majors** arrive one line at a time (`separateMultipleMajor`): a v1 → v3 jump produces a PR for the latest v2 first and then one for v3 — the stepwise procedure the versioning section requires.
-- `prConcurrentLimit: 10` / `prHourlyLimit: 4` keep the k3d install-tests from all starting at once.
+The config is aligned with the one in `cluster-config`, because the same `jlab-renovate-bot` instance serves both and two repos that behave differently under one bot is a source of surprises rather than of safety.
+
+- **Automerge is global** (`automerge: true`, `automergeType: "pr"`, `platformAutomerge: true`) — every update type, **majors included**. The safeguard is not the absence of automerge, it is the branch protection: `main` requires a **review** and requires `validate-charts` to pass. `platformAutomerge` arms the PR on the forge, and Gitea merges it when *both* conditions are met, so an armed PR without a review simply sits there. This is the setting the older `platformAutomerge: false` comment in `renovate.json5` named as the better one "once required checks exist on `main`" — they now do. Same reasoning as `cluster-config`, which retired its dashboard-approval step for it.
+- **`minimumReleaseAge: "3 days"`** for `patch`, `minor` and `digest` updates. Renovate does not even open the PR before then. A merge here is never just a merge — a chart publish follows it straight away — so a release that gets yanked hours after it appeared must not reach the registry. Majors carry no age gate: they are held at the review, not by a delay.
+- **Majors** arrive one line at a time (`separateMultipleMajor`): a v1 → v3 jump produces a PR for the latest v2 first and then one for v3 — the stepwise procedure the versioning section requires. `separateMinorPatch: true` likewise splits minor and patch into separate PRs, so one red install-test does not block unrelated updates.
+- **No PR caps** (`prConcurrentLimit: 100`, `prHourlyLimit: 0`), as in `cluster-config`. The known cost, written down rather than discovered: the first run after a quiet week can open many PRs at once, and every chart PR starts a k3d install-test — which on a Gitea runner queues inside one job rather than fanning out (see "Where this repo lives"). That queue is the accepted trade for not having updates trickle in four per hour.
+- **`config:best-practices`** is in `extends`. Two of its members matter here: `helpers:pinGitHubActionDigests` moves the workflow files from `actions/checkout@v7` to SHA pins (wanted), and `docker:pinDigests` is switched off again for `custom.regex` and `helm-values` — an `appVersion:` is a tag by construction (`<repo>:{{ .Chart.AppVersion }}`, and the `+up` suffix is built from the same string), so a digest has nowhere to go. Sidecar digests in `values.yaml` *could* be pinned; that is a separate decision, since each digest change would be a chart patch plus a publish.
 - The manually dispatched `change-app-version.yml` still exists for one-off bumps, but the normal path for app updates is now a Renovate PR.
 
 ## Creating a new chart