feat(gitea): upgrade 1.27.3 -> 28.3.0

Gitea dropped the "1." prefix; 28.x is the successor of 1.27.
- image 28.3.0, update.range >=28.0.0 <29.0.0, Renovate ceiling <29.0.0
- drop GITEA__server__DOMAIN (no longer read in 28, ROOT_URL is the source)
- declare RUN_RETENTION_DAYS=400, EGRESS_MODE=lax (no allow list: the OIDC
  login source is not gated by the egress policy in 28.3.0), and
  DISABLE_REGISTRATION=true (28's new default)
- document autoRollbackOnFailedHealth as inert (no ImagePolicy is rendered);
  rollback is a PVC restore because the DB migration is one-way

Co-Authored-By: Claude Opus 5.5 <[email protected]>

apps/wave-0/gitea.yaml

@@ -78,7 +78,7 @@ spec:
     spec:
       containers:
       - name: gitea
-        image: gitea/gitea:1.27.3
+        image: gitea/gitea:28.3.0
         ports:
         - containerPort: 3000
         env:
@@ -89,14 +89,18 @@ spec:
             secretKeyRef:
               name: gitea-bootstrap
               key: secret-key
-        - name: GITEA__server__DOMAIN
-          value: gitea.${BASE_DOMAIN}
         - name: GITEA__server__ROOT_URL
           value: https://gitea.${BASE_DOMAIN}/
         - name: GITEA__actions__ENABLED
           value: 'true'
         - name: GITEA__actions__DEFAULT_ACTIONS_URL
           value: github
+        - name: GITEA__actions__RUN_RETENTION_DAYS
+          value: '400'
+        - name: GITEA__security__EGRESS_MODE
+          value: lax
+        - name: GITEA__service__DISABLE_REGISTRATION
+          value: 'true'
         - name: GITEA_ADMIN_USERNAME
           valueFrom:
             secretKeyRef: