ci: add Gitea Actions workflows (CI/deploy + weekly npm audit)

- ci.yml: run Playwright tests on every push to main, then deploy to VPS
  if tests pass; includes post-deploy health check
- audit.yml: weekly npm audit (Mondays 07:00 UTC), fails on high/critical
- Requires VPS_SSH_KEY secret (already configured in repo settings)

.gitea/workflows/audit.yml

@@ -0,0 +1,27 @@
+name: Security · npm audit
+
+on:
+  schedule:
+    # Each Monday at 07:00 UTC
+    - cron: '0 7 * * 1'
+  workflow_dispatch:
+
+jobs:
+  audit:
+    name: npm audit
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Run audit (fail on high/critical)
+        run: npm audit --audit-level=high