ci: checkout 改為完整歷史（fetch-depth: 0）

預設淺層 clone 只有一個 commit，Claude 需要完整歷史才能比對分支與產生 diff。

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.gitea/workflows/claude.yml

@@ -14,6 +14,8 @@ jobs:
     runs-on: yellow-zeabur-runner
     steps:
       - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
       - uses: markwylde/claude-code-gitea-action@v1.0.20
         with:
           anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}