fix: 去掉actions/checkout依赖，改用git clone避免GitHub网络问题

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitea/workflows/release-docs.yml

@@ -10,7 +10,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        env:
+          GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}
+        run: |
+          git clone -b ${GITHUB_REF#refs/tags/} \
+            "https://gitea-actions:${GITEA_TOKEN}@${{ github.server_url }}/${{ github.repository }}.git" .
 
       - name: Package docs
         run: |
@@ -30,7 +34,7 @@ jobs:
           API="${{ github.server_url }}/api/v1/repos/${{ github.repository }}"
           AUTH="Authorization: token ${GITEA_TOKEN}"
 
-          # Delete existing release for this tag if any (ignore errors)
+          # Delete existing release for this tag if any
           EXISTING_ID=$(curl -sf "${API}/releases/tags/${TAG}" -H "$AUTH" 2>/dev/null \
             | python3 -c "import sys,json; print(json.load(sys.stdin).get('id',''))" 2>/dev/null || true)
           if [ -n "$EXISTING_ID" ]; then