debug: Add locale state debugging to i18n workflow

Add debug step to check:
- If subscription section exists in source (en) locale
- If subscription section exists in target (zh) locale
- Git working tree status before commit

This will help diagnose why lobe-i18n isn't generating changes.

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

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

Author: snomiao

.github/workflows/i18n-update-core.yaml

@@ -44,6 +44,14 @@ jobs:
       run: pnpm locale
       env:
         OPENAI_API_KEY: ${{ secrets.OPENAI_API_KEY }}
+    - name: Debug locale state
+      run: |
+        echo "=== Checking if subscription exists in source (en) ==="
+        jq '.subscription | keys' src/locales/en/main.json || echo "No subscription section in en"
+        echo "=== Checking if subscription exists in target (zh) ==="
+        jq '.subscription | keys' src/locales/zh/main.json || echo "No subscription section in zh"
+        echo "=== Git working tree status ==="
+        git status --porcelain src/locales/
     - name: Commit updated locales
       run: |
         git config --global user.name 'github-actions'