feat: PKCE auth + CI/CD deploy

- Frontend: PKCE flow (oauth.ts, AuthCallback code exchange, 401 interceptor)
- Backend: token introspection via SuperOAuth (no more JWT secret)
- User model: superOauthId (unified) replaces oauthId+provider
- Cookies httpOnly session + refresh token
- POST /auth/refresh endpoint
- Gitea CI workflow (vps-runner pattern)
- DB_SYNC env var for initial schema creation

frontend/.gitignore

@@ -0,0 +1,24 @@
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+lerna-debug.log*
+
+node_modules
+dist
+dist-ssr
+*.local
+
+# Editor directories and files
+.vscode/*
+!.vscode/extensions.json
+.idea
+.DS_Store
+*.suo
+*.ntvs*
+*.njsproj
+*.sln
+*.sw?