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

searxng/templates/NOTES.txt

@@ -1,20 +1,68 @@
 {{- $replicas := include "searxng.replicas" (dict "scaleDown" .Values.scaleDown "replicas" .Values.searxng.replicas) -}}
 {{- $settings := fromYaml (include "searxng.effectiveSettings" .Values.settings) -}}
+{{- $httpRoute := .Values.httpRoute | default dict -}}
+{{- $hostnames := $httpRoute.hostnames | default list -}}
+{{- if not $hostnames -}}
+{{- $hostnames = list .Values.ingress.domain -}}
+{{- end -}}
 SearXNG {{ .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 }}"
   cluster issuer. Until it has been issued the browser shows a warning; follow it with
 
     kubectl -n {{ .Release.Namespace }} get certificate tls-{{ .Release.Name }}-{{ .Chart.Name }}-ingress
+{{- 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.
+
+  SEARXNG_BASE_URL still follows ingress.domain ("https://{{ .Values.ingress.domain }}/"), not
+  httpRoute.hostnames: signed image-proxy URLs and the OpenSearch description
+  keep naming that host whatever the route publishes.
+
+  AND THE THING THIS MODE TAKES AWAY: the forward-auth escape hatch. The
+  Gateway API has no annotation channel, so the Authentik-style auth
+  annotations documented under ingress.annotations in values.yaml have NO
+  counterpart here, and the chart renders no implementation-specific policy
+  object on purpose. SearXNG has no login of its own, so "who may use this
+  instance" is entirely the Gateway's question in this mode — a listener that
+  is not publicly reachable, or that implementation's own auth filter,
+  configured next to the Gateway and not here.
 {{- 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.domain is still required: it builds SEARXNG_BASE_URL, which SearXNG
   puts into its OpenSearch description, into the signed image-proxy URLs and
   into every absolute link. Reach the instance inside the cluster with
@@ -28,7 +76,10 @@ ACCESS — NO INGRESS
 SCALED TO ZERO
   {{ if .Values.scaleDown }}scaleDown: true{{ else }}searxng.replicas: 0{{ end }} — the deployment runs with replicas: 0, so the endpoint
   above does not answer until you set it back and upgrade again. Service{{ if .Values.ingress.enabled }} and
-  Ingress stay in place, so the certificate is not re-issued.{{ else }} stays in
+  Ingress stay in place, so the certificate is not 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 rather than with
+  nothing.{{ else }} stays in
   place.{{ end }}
 {{ end }}
 CONFIGURATION
@@ -48,14 +99,25 @@ WHAT THE GREEN CHECKMARK DOES AND DOES NOT MEAN
   All three probes hit /healthz, the only path SearXNG's bot detection lets
   through unconditionally. Its handler returns a fixed "OK". So a Ready pod
   means the worker answers — not that a search works, not that any engine is
-  reachable, and not that a login placed in front of the Ingress is up (probes
-  go straight to the pod and never pass the Ingress).
+  reachable, and not that a login placed in front of it is up (probes go
+  straight to the pod and never pass the {{ if $httpRoute.enabled }}Gateway{{ else }}Ingress{{ end }}).
 {{- if not $settings.limiter }}
 
 BOT DETECTION IS OFF
+{{- if $httpRoute.enabled }}
+  settings.limiter is false and no Valkey is configured. The instance relies on
+  whatever sits in front of it — and in GATEWAY MODE that cannot be configured
+  from this chart: ingress.annotations has no counterpart, so a login has to be
+  put on the Gateway itself (a listener that is not publicly reachable, or that
+  implementation's own auth filter). The limiter itself is unaffected by the
+  mode; it runs inside SearXNG, not at the proxy.
+{{- else }}
   settings.limiter is false and no Valkey is configured. The instance relies on
   whatever sits in front of it — put authentication there via
-  ingress.annotations if it must not be open to everyone.
+  ingress.annotations if it must not be open to everyone. Mind that this
+  escape hatch exists in Ingress mode only: httpRoute.enabled has no
+  annotation channel at all.
+{{- end }}
 {{- else if not .Values.secrets.valkeySecretRef }}
 
 BOT DETECTION IS ON WITHOUT A VALKEY