chore(renovate): require manual review for privileged CI image digest bumps

Adds a packageRule matching .gitea/workflows/** digest updates with
automerge: false. Digest bumps for images running --privileged --pid=host
have root-equivalent host access and must not be auto-merged.

Addresses Nora's review concern on #537.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

renovate.json

@@ -5,6 +5,13 @@
       "matchPackagePatterns": ["^@tiptap/"],
       "groupName": "tiptap",
       "automerge": false
+    },
+    {
+      "description": "Digest bumps for images used in privileged CI steps (--privileged --pid=host) must be reviewed manually — a compromised image has root-equivalent host access.",
+      "matchPaths": [".gitea/workflows/**"],
+      "matchUpdateTypes": ["digest"],
+      "automerge": false,
+      "reviewersFromCodeOwners": false
     }
   ]
 }