ci(workflow): validate i18n locale files are synchronized (#2347)

.github/workflows/ci.yml

@@ -22,6 +22,69 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
+  i18n:
+    name: i18n Check
+    if: github.event_name == 'pull_request'
+    runs-on: ubuntu-24.04
+    permissions:
+      contents: read
+      pull-requests: write
+    env:
+      GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      GH_REPO: ${{ github.repository }}
+      NUMBER: ${{ github.event.pull_request.number }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5.0.1
+        with:
+          persist-credentials: false
+
+      - name: Pnpm Setup
+        uses: pnpm/action-setup@41ff72655975bd51cab0327fa583b6e92b6d3061 # v4.2.0
+
+      - name: Set up Node.js
+        uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5.0.0
+        with:
+          node-version-file: 'package.json'
+
+      - name: Get pnpm store directory
+        shell: bash
+        run: echo "STORE_PATH=$(pnpm store path --silent)" >> $GITHUB_ENV
+
+      - name: Setup pnpm cache
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
+        with:
+          path: ${{ env.STORE_PATH }}
+          key: ${{ runner.os }}-pnpm-store-${{ hashFiles('**/pnpm-lock.yaml') }}
+          restore-keys: |
+            ${{ runner.os }}-pnpm-store-
+
+      - name: Install dependencies
+        env:
+          CI: true
+        run: pnpm install
+
+      - name: i18n Check
+        shell: bash
+        env:
+          BODY: |
+            The i18n check failed because translation messages are out of sync.
+
+            This usually happens when you've added or modified translation strings in your code but haven't updated the translation file.
+
+            Please run `pnpm i18n:extract` and commit the changes.
+        run: |
+          retry() { n=0; until "$@"; do n=$((n+1)); [ $n -ge 3 ] && break; echo "retry $n: $*" >&2; sleep 2; done; }
+          node bin/check-i18n.js
+          check_failed=$?
+          if [ $check_failed -eq 1 ]; then
+            retry gh pr edit "$NUMBER" -R "$GH_REPO" --add-label "i18n-out-of-sync" || true
+            retry gh pr comment "$NUMBER" -R "$GH_REPO" -b "$BODY" || true
+          else
+            retry gh pr edit "$NUMBER" -R "$GH_REPO" --remove-label "i18n-out-of-sync" || true
+          fi
+          exit $check_failed
+
   test:
     name: Lint & Test Build
     if: github.event_name == 'pull_request'