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

bentopdf/values.yaml

@@ -174,13 +174,30 @@ ingress:
   # read inside the Ingress template - unlike searxng, this chart has no
   # second reader of ingress.domain: the upstream counterpart BASE_URL is a
   # build-time argument and empty in the published image).
+  #
+  # Mutually exclusive with httpRoute.enabled below (Gitea #114): with both
+  # true the render aborts, naming both values. In Gateway mode ingress.domain
+  # is read again - by the HTTPRoute, as its single hostname - so "both modes
+  # off" is what frees it, not "ingress off".
   enabled: true
   clusterIssuer: null
+  # The public hostname of this release. Read by the Ingress AND - when
+  # httpRoute.hostnames is empty - by the HTTPRoute, so it stays the single
+  # source of truth for the hostname in both modes.
   domain: null
   className: nginx
   # Extra annotations for the Ingress; merged with the cert-manager
   # cluster-issuer annotation the chart always sets.
   #
+  # THESE HAVE NO COUNTERPART IN GATEWAY MODE, AND FOR THIS CHART THAT COSTS
+  # SOMETHING CONCRETE. The Gateway API has no annotation channel for
+  # controller behaviour, so both uses documented below - the X-Robots-Tag
+  # header and any repair for a controller that mangles the headers or the
+  # .mjs MIME type - are simply gone when httpRoute.enabled is used instead.
+  # The chart does not rebuild them: a policy object would bind it to one
+  # Gateway implementation. It is then the Gateway's business. NOTES.txt says
+  # so in that mode.
+  #
   # TWO HEADERS MUST SURVIVE THE PROXY, OR OFFICE CONVERSION BREAKS. The image
   # sends Cross-Origin-Opener-Policy: same-origin and
   # Cross-Origin-Embedder-Policy: credentialless. Together they make the page
@@ -212,6 +229,48 @@ ingress:
   # add-headers ConfigMap is the alternative.
   annotations: {}
 
+# Gateway-API alternative to the Ingress above (Gitea #114). Off by default, so
+# an existing release is unaffected; exactly one of ingress.enabled and
+# httpRoute.enabled may be true.
+#
+# The chart renders ONLY an HTTPRoute with parentRefs - no Gateway, no
+# gatewayClassName, no Certificate and no implementation-specific policy
+# object. Class and certificate belong to the Gateway and therefore to the
+# platform, which is what keeps this chart independent of whether the cluster
+# runs nginx-gateway-fabric, Cilium, Envoy Gateway or Istio.
+#
+# The Gateway-API CRDs must be installed in the cluster: the chart does not and
+# cannot detect them (.Capabilities.APIVersions is unreliable at template
+# time), so with httpRoute.enabled: true and no CRDs the INSTALL fails.
+#
+# WHAT THIS MODE COSTS HERE: the whole ingress.annotations escape hatch above,
+# including the X-Robots-Tag header - a public instance in Gateway mode gets
+# indexed unless the Gateway adds the header. The two cross-origin headers are
+# a different case: the image sends them itself, so they still arrive in this
+# mode unless something in the path strips them (NOTES.txt has the curl).
+httpRoute:
+  enabled: false
+  # The Gateway(s) this route attaches to - a platform object, usually in
+  # another namespace, which must allow this namespace in its listener's
+  # allowedRoutes. One entry per parent, the fields are the Gateway API's
+  # ParentReference (name, and optionally namespace, sectionName, port, group,
+  # kind), passed through unchanged:
+  #
+  #   parentRefs:
+  #     - name: public
+  #       namespace: gateway
+  #       sectionName: https
+  #
+  # REQUIRED while httpRoute.enabled is true - the render aborts on an empty
+  # list, because a route without a parent is created, is valid and routes
+  # nothing, with no event to say so.
+  parentRefs: []
+  # Empty means [ingress.domain], so the hostname has one source of truth. Set
+  # explicitly only to publish under a different or an additional name - which
+  # is how a migration from the Ingress runs: the HTTPRoute takes a second
+  # hostname while the Ingress keeps ingress.domain.
+  hostnames: []
+
 # WHAT THIS CHART CANNOT DO
 #
 # Almost everything else about BentoPDF is a BUILD-TIME argument and therefore