ci: add web frontend lint and type check workflow (#2444)

Add a dedicated GitHub Actions workflow for the Next.js web frontend
that runs on changes to the web/ directory:

- ESLint checks via 'npm run lint'
- TypeScript type checking via 'tsc --noEmit'
- Runs on push to main and PRs targeting main
- Uses npm cache for faster dependency installation

Co-authored-by: Hu Qiantao <huqiantao@HudeMacBook-Air.local>

.github/workflows/web.yml

@@ -0,0 +1,35 @@
+name: Web Frontend
+
+on:
+  push:
+    branches: [master, main]
+    paths:
+      - 'web/**'
+  pull_request:
+    branches: [master, main]
+    paths:
+      - 'web/**'
+
+permissions:
+  contents: read
+
+jobs:
+  lint:
+    name: Lint & Type Check
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: web
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: 'npm'
+          cache-dependency-path: web/package-lock.json
+      - name: Install dependencies
+        run: npm ci
+      - name: Run ESLint
+        run: npm run lint
+      - name: TypeScript type check
+        run: npx tsc --noEmit