ci: add pull-request quality checks

.github/workflows/quality.yml

@@ -0,0 +1,60 @@
+name: Code Quality
+
+on:
+  pull_request:
+    types: [opened, reopened, synchronize, ready_for_review]
+  push:
+    branches: [main]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  quality:
+    name: Repository quality
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    env:
+      CI: true
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+        with:
+          persist-credentials: false
+
+      - name: Setup Node.js
+        uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
+        with:
+          node-version: '22'
+          cache: npm
+          cache-dependency-path: package-lock.json
+
+      - name: Install dependencies
+        id: install
+        run: npm ci --ignore-scripts
+
+      - name: Typecheck
+        if: ${{ !cancelled() && steps.install.outcome == 'success' }}
+        run: npx tsc --noEmit
+
+      - name: Lint
+        if: ${{ !cancelled() && steps.install.outcome == 'success' }}
+        run: npm run lint
+
+      - name: Test
+        if: ${{ !cancelled() && steps.install.outcome == 'success' }}
+        run: npm test
+
+      # Main currently has known locale-parity debt covered by PR #710. Keep the
+      # check visible without blocking unrelated PRs; make it required once that
+      # existing translation PR (or an equivalent fix) lands.
+      - name: Check translations (advisory)
+        if: ${{ !cancelled() && steps.install.outcome == 'success' }}
+        continue-on-error: true
+        run: npm run i18n:check