chore: add auto-format workflow and fix formatting (#319)

- Add GitHub Action to auto-format PRs with Biome
- Fix formatting in app/manifest.ts and scripts/test-diagram-operations.mjs

.github/workflows/auto-format.yml

@@ -0,0 +1,47 @@
+name: Auto Format
+
+on:
+  pull_request:
+    types: [opened, synchronize]
+
+permissions:
+  contents: write
+
+jobs:
+  format:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.head_ref }}
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+
+      - name: Install Biome
+        run: npm install --save-dev @biomejs/biome
+
+      - name: Run Biome format
+        run: npx @biomejs/biome check --write --no-errors-on-unmatched .
+
+      - name: Check for changes
+        id: changes
+        run: |
+          if git diff --quiet; then
+            echo "has_changes=false" >> $GITHUB_OUTPUT
+          else
+            echo "has_changes=true" >> $GITHUB_OUTPUT
+          fi
+
+      - name: Commit changes
+        if: steps.changes.outputs.has_changes == 'true'
+        run: |
+          git config --global user.name "github-actions[bot]"
+          git config --global user.email "github-actions[bot]@users.noreply.github.com"
+          git add .
+          git commit -m "style: auto-format with Biome"
+          git push