ci: add Gitea Actions workflow for build + test on push/PR

Runs on every push to main and every PR:
  1. npm ci       — install deps
  2. npm run build — TypeScript type check
  3. npm test      — vitest run (216 tests, all mocked, no DB/Redis needed)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -0,0 +1,31 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '22'
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Type check
+        run: npm run build
+
+      - name: Run tests
+        run: npm test
+        env:
+          NODE_ENV: test