feat: Gateway-API as an alternative to the Ingress in eight charts

Group 1 of the #114 sweep: the charts that render exactly one Ingress object
and set no behaviour-bearing nginx annotation - bentopdf, garage, patchmon,
rallly, searxng, sure, urlaubsverwaltung, voucher-vault.

Each gets the form the pilot (cyberchef, PR #115) fixed and template-chart
carries: an httpRoute block (enabled/parentRefs/hostnames, off by default), a
template rendering ONLY an HTTPRoute with parentRefs - no Gateway, no
gatewayClassName, no Certificate, no implementation-specific policy object -
render aborts on both modes at once (naming both value paths), on an empty
parentRefs and on a missing hostname, empty hostnames meaning [ingress.domain],
a schema entry closed against unknown keys with an open parentRef definition,
and a NOTES.txt that names the active mode and what the mode costs.

Minor, additive, defaults unchanged: `helm template` with each chart's CI
values is byte-identical to origin/main for seven of the eight, and for sure
identical in every rendered value (the diff is two YAML comment lines).

Three findings that were not in the plan, each argued in the file it changes:

  sure derived RAILS_ASSUME_SSL/RAILS_FORCE_SSL from ingress.enabled alone.
  Gateway mode sets that false by construction while TLS is still terminated at
  the Gateway, so both flags would have gone false: insecure cookies, no HSTS,
  http:// links, with a Ready pod and a working UI as the only symptom. They now
  read sure.publishedOverTls (ingress.enabled OR httpRoute.enabled), which is
  ingress.enabled while httpRoute.enabled is false - hence still Minor.

  garage claimed, in its Ingress template and its schema, that nothing outside
  that template reads ingress.domain. The HTTPRoute reads it, so the claim now
  holds only while both modes are off. Corrected rather than left standing.

  garage also depends on an upload limit it does not set: its annotations
  comment tells the operator to set proxy-body-size: "0" because ingress-nginx
  truncates S3 uploads at 1 MB. proxy-body-size has no Gateway-API counterpart,
  so its Gateway-mode NOTES prints that the limit is the Gateway's. README's
  list of affected charts named five and now names garage as a sixth.

clusterIssuer needed no change in any of the eight: its only required() sits
inside the Ingress template behind ingress.enabled, the same no-op the pilot
found. Annotation guidance that stops applying in Gateway mode moved into the
Gateway branch of NOTES.txt for bentopdf (X-Robots-Tag) and searxng
(forward-auth).

CI: one render overlay per chart under ci/httproute/, so the assertion is not
vacuum-green - ci/run-httproute-match-test.sh goes from 4 held assertions over
2 charts to 20 over 10. The install-test fixtures stay in Ingress mode: the
install runs one configuration per chart, cyberchef already pays that price
against the real Gateway-API CRDs, and for garage the Ingress is the only place
its Service port is referenced by NAME.

Not proven, by construction: that traffic flows. No Gateway controller runs in
CI. Not run locally either: k3d, Docker, Trivy.

Part of #114

voucher-vault/templates/NOTES.txt

@@ -11,11 +11,16 @@
 {{- range $required := list "DOMAIN" "SECRET_KEY" "REDIS_URL" "DB_ENGINE" "POSTGRES_HOST" "POSTGRES_DB" }}
 {{- if not (has $required $names) }}{{- $missing = append $missing $required }}{{- end }}
 {{- end }}
+{{- $httpRoute := .Values.httpRoute | default dict -}}
+{{- $hostnames := $httpRoute.hostnames | default list -}}
+{{- if not $hostnames -}}
+{{- $hostnames = list .Values.ingress.domain -}}
+{{- end -}}
 VoucherVault {{ .Chart.AppVersion }} — release {{ .Release.Name }} in namespace {{ .Release.Namespace }}.
 
 {{- if .Values.ingress.enabled }}
 
-ACCESS
+ACCESS — INGRESS MODE (ingress.enabled: true, httpRoute.enabled: false)
   https://{{ .Values.ingress.domain }}
 
   The certificate is requested by cert-manager through the "{{ .Values.ingress.clusterIssuer }}"
@@ -26,10 +31,51 @@ ACCESS
   ingress.domain is more than the Ingress host: it is the only entry Django adds
   to ALLOWED_HOSTS besides 127.0.0.1, and it builds CSRF_TRUSTED_ORIGINS. Under
   any other name the app answers 400 before a single view runs.
+{{- else if $httpRoute.enabled }}
+
+ACCESS — GATEWAY MODE (httpRoute.enabled: true, ingress.enabled: false)
+{{- range $hostnames }}
+  https://{{ . }}
+{{- end }}
+
+  This release renders an HTTPRoute ({{ .Release.Name }}-{{ .Chart.Name }}-httproute) and NOTHING else
+  of the routing path — no Gateway, no class, no Certificate. Three things
+  therefore belong to the cluster and not to this chart:
+
+    1. The Gateway-API CRDs. Without them this install would have failed.
+    2. The Gateway named in httpRoute.parentRefs
+{{- range $httpRoute.parentRefs }}
+         {{ .name }}{{ if .namespace }} in namespace {{ .namespace }}{{ end }}{{ if .sectionName }}, listener {{ .sectionName }}{{ end }}
+{{- end }}
+       must exist AND its listener must allow routes from this namespace
+       ({{ .Release.Namespace }}) in allowedRoutes. A rejected attachment shows
+       up only in the route's status:
+
+         kubectl -n {{ .Release.Namespace }} get httproute {{ .Release.Name }}-{{ .Chart.Name }}-httproute -o yaml
+
+       Read status.parents[].conditions — "Accepted: True" and
+       "ResolvedRefs: True" is a working attachment. An empty status means no
+       controller has looked at the route at all.
+    3. The TLS certificate for the hostname, on the Gateway's listener.
+       ingress.clusterIssuer is NOT used in this mode and is not required: the
+       chart renders no Certificate, so there is no
+       tls-{{ .Release.Name }}-{{ .Chart.Name }}-ingress secret and nothing for cert-manager to do.
+
+  AND THE ONE THAT WILL ACTUALLY BITE: ALLOWED_HOSTS DOES NOT FOLLOW THE ROUTE.
+  Django's DOMAIN is built from ingress.domain ("{{ .Values.ingress.domain }}"), and that is the
+  only name besides 127.0.0.1 it accepts. A hostname this route publishes which
+  ingress.domain does not name is answered with 400 before a single view runs —
+  and all three probes stay green while it happens, because they deliberately
+  carry a Host header of 127.0.0.1 so that probing survives every domain
+  change. So set httpRoute.hostnames and ingress.domain together.
+
+  ingress.annotations is inert in this mode: the Gateway API has no annotation
+  channel. Nothing this chart needs lives there.
 {{- else }}
 
-ACCESS — NO INGRESS
-  ingress.enabled is false, so this release has no Ingress and no certificate;
+ACCESS — NEITHER INGRESS NOR HTTPROUTE
+  ingress.enabled and httpRoute.enabled are both false, so this release has no
+  Ingress, no HTTPRoute and no certificate;
   ingress.clusterIssuer is not needed. ingress.domain still is — it is Django's
   ALLOWED_HOSTS entry ("{{ .Values.ingress.domain }}"), not just an Ingress host.
 
@@ -58,7 +104,8 @@ SCALED TO ZERO
   {{ if .Values.scaleDown }}scaleDown: true{{ else }}voucherVault.replicas: 0{{ end }} — the StatefulSet runs with replicas: 0, so the endpoint
   above does not answer until you set it back and upgrade again. PVC, Secrets
   and Service{{ if .Values.ingress.enabled }} and Ingress stay in place, so the certificate is not
-  re-issued.{{ else }} stay in place.{{ end }}
+  re-issued.{{ else if $httpRoute.enabled }} and HTTPRoute stay in place, so the route keeps pointing at a
+  Service with no endpoints — the Gateway answers with an error of its own.{{ else }} stay in place.{{ end }}
 {{ end }}
 SECRETS — THE FIELDS EACH 1PASSWORD ITEM MUST CARRY
   All three OnePasswordItem CRs are created unconditionally and carry an item
@@ -87,7 +134,7 @@ SECRETS — THE FIELDS EACH 1PASSWORD ITEM MUST CARRY
   endpoint is a field and not an optional extra. The redirect URI to register at
   the provider is
 
-    https://{{ if .Values.ingress.enabled }}{{ .Values.ingress.domain }}{{ else }}example.com{{ end }}/oidc/callback/
+    https://{{ if or .Values.ingress.enabled $httpRoute.enabled }}{{ first $hostnames }}{{ else }}example.com{{ end }}/oidc/callback/
 
   and it carries no language prefix, unlike every other path of the app.
 {{- if $missing }}
@@ -137,8 +184,8 @@ WHAT A READY POD DOES NOT PROVE
   wrong ingress.domain is invisible to Kubernetes — all three probes pass, the
   rollout goes green, and every real request gets 400. Check it against the
   domain instead:
-{{ if .Values.ingress.enabled }}
-    curl -sI https://{{ .Values.ingress.domain }}/ | head -1
+{{ if or .Values.ingress.enabled $httpRoute.enabled }}
+    curl -sI https://{{ first $hostnames }}/ | head -1
 {{- else }}
     curl -sI http://127.0.0.1:8000/ | head -1     # through the port-forward above
 {{- end }}