Rotate gitea SECRET_KEY into its own claim, drop gitea-random

Completes the post-breach (CVE-2026-59774) secret split. SECRET_KEY moves
from the shared gitea-random claim to a dedicated gitea-secret-key claim
with a fresh value, and the now-unused gitea-random claim is removed
(ArgoCD prunes it).

The earlier concern that rotating SECRET_KEY breaks the 2 push mirrors was
wrong: their gitlab.com credentials live in each repo's on-disk git config,
not in SECRET_KEY-encrypted storage. Blast radius here is negligible: 0 TOTP
2FA, 0 Actions secrets, 0 runner tokens, pull mirrors are public. SECRET_KEY
has no length constraint (Gitea hashes it to derive the AES key), so unlike
JWT_SECRET size 32 is fine and is not regenerated.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

gitea/application.yaml

@@ -16,28 +16,22 @@ spec:
 
 # Gitea DOES NOT go through Traefik. It has its own IP because ssh :22 would conflict with kube worker ssh. On its own IP, at the moment it doesn't flirt with Traefik — also has its own certificate.
 ---
-# After the 2026-09 breach (CVE-2026-59774) all three secrets below leaked
-# because they shared one generated value. INTERNAL_TOKEN and JWT_SECRET were
-# moved to their own claims (gitea-internal-token, gitea-oauth2-jwt) and rotated;
-# the StatefulSet now reads those two from the new claims, so the copies here are
-# unused. SECRET_KEY is intentionally still sourced from this claim and NOT
-# rotated: a new value would make data-at-rest (push-mirror creds, 2FA)
-# undecryptable and break the 2 push mirrors, whose credentials must be re-entered
-# by hand. Do not shrink this mapping: the operator would regenerate the plaintext
-# and change SECRET_KEY. Rotate SECRET_KEY in a maintenance window instead.
+# After the 2026-09 breach (CVE-2026-59774) all three security secrets leaked
+# because they shared one generated value from a single "gitea-random" claim.
+# Each now has its own claim and a fresh value: gitea-secret-key,
+# gitea-internal-token and gitea-oauth2-jwt. The old shared gitea-random claim
+# was removed. SECRET_KEY has no length constraint (Gitea hashes it to derive the
+# AES key), so size 32 is fine; the earlier worry about push mirrors was wrong:
+# their credentials live in each repo's on-disk git config, not SECRET_KEY.
 apiVersion: codemowers.cloud/v1beta1
 kind: SecretClaim
 metadata:
-  name: gitea-random
+  name: gitea-secret-key
 spec:
   size: 32
   mapping:
     - key: GITEA__SECURITY__SECRET_KEY
       value: "%(plaintext)s"
-    - key: GITEA__SECURITY__INTERNAL_TOKEN
-      value: "%(plaintext)s"
-    - key: GITEA__OAUTH2__JWT_SECRET
-      value: "%(plaintext)s"
 ---
 apiVersion: codemowers.cloud/v1beta1
 kind: SecretClaim
@@ -264,7 +258,7 @@ spec:
             - name: GITEA__SECURITY__SECRET_KEY
               valueFrom:
                 secretKeyRef:
-                  name: gitea-random
+                  name: gitea-secret-key
                   key: GITEA__SECURITY__SECRET_KEY
           ports:
             - containerPort: 8080