debug: Add detailed git diff output to format_dart workflow

- Show git status before and after dart format
- Show git diff to see exactly what formatting changes are made
- This will help debug why local formatting differs from CI
- Helps identify the root cause of format_dart failures

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: ened

.github/workflows/format.yml

@@ -16,6 +16,15 @@ jobs:
           channel: 'stable'
       - name: Format
         run: |
+          echo "=== Git status before formatting ==="
+          git status --porcelain
+          echo "=== Running dart format ==="
+          dart format .
+          echo "=== Git diff after formatting ==="
+          git diff
+          echo "=== Git status after formatting ==="
+          git status --porcelain
+          echo "=== Now running with --set-exit-if-changed ==="
           dart format --set-exit-if-changed .
 
   format_kotlin: