feat: PKCE auth + CI/CD deploy

- Frontend: PKCE flow (oauth.js, api.js centralized, cookie-based AuthContext)
- Backend: token introspection, cookies httpOnly, refresh endpoint
- Replaced localStorage JWT with httpOnly session cookies
- useSaveSync migrated to cookie auth
- cookie-parser added
- Gitea CI workflow (vps-runner pattern)

.gitea/workflows/deploy.yml

@@ -0,0 +1,57 @@
+name: CI/CD — Build & Deploy
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  build-and-deploy:
+    name: Build & Deploy
+    runs-on: vps-runner
+
+    steps:
+      - uses: actions/checkout@v4
+
+      # ── Backend ──────────────────────────────────────────────────────────────
+      - name: Install backend deps
+        working-directory: Backend
+        run: npm ci --omit=dev
+
+      - name: Deploy backend
+        if: github.event_name == 'push' && github.ref == 'refs/heads/main'
+        run: |
+          mkdir -p /var/www/clickerz/backend
+          rsync -a --delete --exclude=node_modules --exclude=.env Backend/ /var/www/clickerz/backend/
+          cd /var/www/clickerz/backend && npm ci --omit=dev
+
+      - name: Restart pm2
+        if: github.event_name == 'push' && github.ref == 'refs/heads/main'
+        run: |
+          su - tetardtek-brain -c 'pm2 reload clickerz-backend --update-env'
+
+      # ── Frontend ─────────────────────────────────────────────────────────────
+      - name: Install & build frontend
+        working-directory: Frontend
+        env:
+          VITE_BACKEND_URL: https://clickerz.tetardtek.com
+          VITE_OAUTH_URL: https://superoauth.tetardtek.com
+          VITE_OAUTH_CLIENT_ID: clickerz
+        run: |
+          npm ci
+          npm run build
+
+      - name: Deploy frontend
+        if: github.event_name == 'push' && github.ref == 'refs/heads/main'
+        run: |
+          mkdir -p /var/www/clickerz/frontend/dist
+          rsync -a --delete Frontend/dist/ /var/www/clickerz/frontend/dist/
+
+      # ── Smoke test ───────────────────────────────────────────────────────────
+      - name: Smoke test API
+        if: github.event_name == 'push' && github.ref == 'refs/heads/main'
+        run: |
+          sleep 3
+          curl -sf http://localhost:3520/api/auth/me 2>&1 | grep -q '401\|session\|Not authenticated'
+          echo "✅ API responds OK"