feat: add husky pre-commit hooks and reusable CI lint workflow

- Add husky with lint-staged for pre-commit checks (eslint --fix, prettier --write)
- Add reusable lint.yml workflow (eslint, prettier, tsc)
- Gate docker, release, and CI pipelines behind lint job via needs: lint

.github/workflows/lint.yml

@@ -0,0 +1,29 @@
+name: Lint & Format
+
+on:
+  workflow_call:
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        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 ESLint
+        run: npm run lint
+
+      - name: Check formatting
+        run: npm run format:check
+
+      - name: Run TypeScript check
+        run: npx tsc --noEmit