Fix: use REGISTRY_TOKEN instead of reserved GITEA_TOKEN

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.gitea/workflows/docker.yaml

@@ -27,7 +27,7 @@ jobs:
         with:
           registry: ${{ env.REGISTRY }}
           username: ${{ gitea.actor }}
-          password: ${{ secrets.GITEA_TOKEN }}
+          password: ${{ secrets.REGISTRY_TOKEN }}
 
       - name: Extract metadata
         id: meta