Pin gluetun in values too, so Renovate proposes it there

The chart bundles nine independently versioned upstreams, and eight of them
were already pinned in values.yaml while only gluetun took its tag from
appVersion. That split had no upside: it made gluetun the one image Renovate
could not reach through the built-in helm-values manager, and it implied a
"main app" the stack does not have.

gluetun now carries gluetun.image.repository/tag like every other image, and
the StatefulSet renders it from there. No tag comes from appVersion any more.
Renovate picks all nine up through helm-values - the manager the repo already
relies on for sidecar images - and ci/renovate-bump-chart.sh bumps the chart
version with each update.

Consequences, all documented where they bite:
- renovate.json5 deliberately gets no app-version block for this chart. One
  would either duplicate the helm-values updates or rewrite an appVersion that
  selects no image. The absence is commented so it does not read as an
  oversight.
- freesailarr leaves the change-app-version.yml choice list. That workflow
  rewrites appVersion and republishes, which for this chart would change no
  deployed image at all.
- appVersion becomes a hand-maintained marker for the gluetun line. Since
  renovate-bump-chart.sh bumps the patch level on an unchanged appVersion, a
  gluetun update has to be paired with a hand edit of appVersion, or the +up
  suffix stops describing what the chart deploys. Noted in Chart.yaml,
  values.yaml and README.

README.md

@@ -66,10 +66,13 @@ What Renovate keeps current:
 | --- | --- |
 | Chart app versions (`appVersion:` in `Chart.yaml`) | One `customManagers` entry per chart, hard-coding the image repository |
 | Sidecar/init images in `values.yaml` (nginx, guacd, busybox, alpine) | Built-in `helm-values` manager |
+| **All** images of `freesailarr`, including its main one | Built-in `helm-values` manager — the chart pins every tag in `values.yaml` and has no app-version block |
 | GitHub Actions | Built-in `github-actions` manager |
 | Tool versions pinned as workflow env vars (`TRIVY_VERSION`) | `# renovate: datasource=… depName=…` comment above the line |
 
-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`, `teamspeak-server`) override `versioning` in their block; the reasoning sits next to each one.
+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`, `teamspeak-server`) override `versioning` in their block; the reasoning sits next to each one. `freesailarr` has no 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.
+
+A consequence of pinning every tag in `values.yaml`: `ci/renovate-bump-chart.sh` sees an unchanged `appVersion` and bumps the chart **patch**, so the `+up` suffix keeps naming the old marker version. That is intended for the eight app images, but it means a **gluetun** update must be paired with a hand edit of `appVersion` (and thus the suffix), otherwise the chart version stops describing what is deployed.
 
 One dependency is constrained beyond its versioning: **nginx** (the Synapse delegation sidecar) is limited to **even minors** via `allowedVersions`. nginx numbers its release branches by minor — even is stable, odd is mainline — and the chart belongs on stable. Patch updates inside the stable branch still flow through normally. The constraint tolerates a variant suffix (`1.30.4-alpine`) on purpose: docker versioning only ever offers candidates carrying the current tag's suffix, so a suffix-blind constraint would silently freeze nginx the day the sidecar moves to a slimmer base image — a switch to `1.30.4-alpine` that #84 has commissioned a check on — with no error and no warning.
 
@@ -143,6 +146,7 @@ These guidelines are **binding for every current and future chart** in this repo
 ### 3. Images
 
 - The main app image tag comes from `{{ .Chart.AppVersion }}` — never hardcoded.
+- **Documented exception — freesailarr**: the chart bundles nine independently versioned upstreams, so none of them is "the" app version. **No** tag comes from `appVersion`; all nine images are pinned as `<app>.image.repository` / `<app>.image.tag` in `values.yaml`, which is also what puts every one of them under the built-in `helm-values` manager. Its `appVersion` is a hand-maintained marker for the gluetun line and is updated together with `gluetun.image.tag`; consequently the chart has **no** block in `renovate.json5` and is **not** in the `change-app-version.yml` choice list.
 - Auxiliary images (sidecars, init containers, secondary workloads — e.g. the delegation nginx in matrix-synapse, guacd in patchmon, busybox init/consume images in paperless-ngx) are pinned via values instead of being hardcoded in templates, and their pinned versions are reviewed alongside every app-version update round.
 
 ### 4. Ingress