feat(bulwark): Gateway-API as an alternative to the Ingress

Group 3 of the #114 sweep. One route, one rule, at the root - and THREE
EXPECTATIONS ABOUT THIS CHART DID NOT SURVIVE CONTACT WITH IT:

  - #114 says bulwark has TWO Ingress objects. It has ONE. keycloak has two.
  - #114's measured table lists bulwark under rewrite-target. It has no
    rewrite-target annotation and CANNOT have one: NEXT_PUBLIC_BASE_PATH is
    compiled into the bundle, so the application cannot be served under a
    sub-path, and stripping a prefix at the proxy would yield a page that
    loads and then fetches everything from the wrong place. Every occurrence
    of the string "rewrite-target" in this chart - values.yaml, the schema,
    the Ingress template - is an explanation of exactly that. A grep for the
    string finds the refutations and counts them as occurrences.
  - ci/run-httproute-match-test.sh said in its header that bulwark was the
    second rewrite-target chart and would meet the #118 prefix/redirect
    assurance when group 3 landed. Group 3 landed and it does not: with no
    URLRewrite on a prefix other than "/", the assurance's precondition is
    never met here. The header is corrected rather than left standing, and it
    now says freesailarr is the only chart the pairing applies to.

So no redirect rule is added, and none is needed.

WHAT THIS MODE DROPS, MEASURED ON THE LIVE OBJECT rather than inferred. On
2026-10-12 the live Ingress on webmail.bekemeyer-klein.de carried

    nginx.ingress.kubernetes.io/proxy-body-size: 25m

supplied by the OPERATOR through ingress.annotations - values.yaml recommends
exactly that value and explains why the chart cannot pick it, so the chart
sets nothing and a reader of this repository alone would not find it. It is
the single annotation this installation depends on, and the Gateway API has no
body-size counterpart: implementation policy, not routing. Per decisions 1 and
2 of #114 it is NAMED, not rebuilt - in values.yaml, in the schema and in the
Gateway branch of NOTES.txt, in this application's own terms: an attachment
above the Gateway's default is rejected before Bulwark sees a byte, the 413
comes from the proxy, and it arrives after the user has written the mail and
attached the file.

CORRECTED CLAIM, the same one garage and calibre-web-automated needed: the
Ingress template, the bulwark.publicUrl helper and the schema all stated that
nothing outside the Ingress template FUNCTIONALLY reads ingress.domain. The
HTTPRoute reads it, so the claim held only while both modes were off. All
three now say so, and the route carries a required() of its own.

bulwark.publicUrl follows the ACTIVE mode instead of always printing
ingress.domain. The two differ exactly when httpRoute.hostnames is set, which
is how a migration off the Ingress runs - and printing the old host there
would hand the operator an OIDC redirect URI for the hostname being migrated
away from, a failure that surfaces as a rejected login at the identity
provider and says nothing about this chart.

Minor: additive, defaults unchanged. Empty helm template diff against
origin/main with ci/bulwark/test-values.yaml.

Part of #114

ci/run-httproute-match-test.sh

@@ -43,9 +43,18 @@
 #     property of one route - a different route is a different hostname and
 #     says nothing about this one. Exact outranks every prefix match in that
 #     precedence, so the pairing is about existence and not about order.
-#     freesailarr is the first chart this applies to; bulwark is the second
-#     rewrite-target chart and meets the same check when group 3 of #114
-#     lands, which is the point of checking it here rather than in one chart.
+#     freesailarr is the FIRST AND, AS OF GROUP 3 OF #114, THE ONLY chart this
+#     applies to. The line that used to stand here said bulwark was the second
+#     rewrite-target chart and would meet the same check when group 3 landed.
+#     Group 3 landed and it does not: bulwark has ONE Ingress object, no
+#     rewrite-target annotation, and cannot have one - NEXT_PUBLIC_BASE_PATH is
+#     compiled into its bundle, so it cannot be served under a sub-path at all
+#     and its route is one rule at "/" with no URLRewrite filter. Every
+#     occurrence of the string "rewrite-target" in that chart is an explanation
+#     of why it does not help, and #114's measured table arrived at "bulwark,
+#     freesailarr" by grepping for the string rather than for the annotation.
+#     The check stays over all charts for the reason below - the mistake
+#     arrives by copy - not because a second chart is known to need it.
 #
 # And the install-test cannot close either gap, even with the real CRDs in the
 # cluster: schema validation accepts an empty parentRefs list and accepts a