Fix Gitea integration: use username/password instead of token

The publish:gitea scaffolder action requires username and password
for Git push operations, not just a token. Changed config to use
GITEA_USERNAME and GITEA_PASSWORD environment variables.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app-config.yaml

@@ -45,7 +45,8 @@ integrations:
   gitea:
     - host: git.rber.bj
       baseUrl: http://git.rber.bj
-      token: ${GITEA_TOKEN}
+      username: ${GITEA_USERNAME}
+      password: ${GITEA_PASSWORD}
 
 proxy:
   ### Example for how to add a proxy endpoint for the frontend.