添加网络诊断和重试机制

- 在 sync_repos.py 中添加Git fetch重试机制（最多3次）
- 优化错误处理和超时管理
- 在 workflow中添加网络连通性诊断步骤
- 提供更详细的错误诊断信息

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

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

.gitea/workflows/multi-repo-sync.yml

@@ -44,6 +44,37 @@ jobs:
         fi
         echo "✓ 配置文件已找到"
 
+    - name: 网络连通性诊断
+      run: |
+        echo "================================================================================"
+        echo "网络连通性诊断"
+        echo "================================================================================"
+        echo ""
+        echo "[1] 检查DNS解析 (center.javablade.com):"
+        if command -v nslookup >/dev/null 2>&1; then
+          nslookup center.javablade.com || echo "❌ nslookup 失败"
+        elif command -v dig >/dev/null 2>&1; then
+          dig center.javablade.com || echo "❌ dig 失败"
+        else
+          getent hosts center.javablade.com || echo "❌ DNS 解析失败"
+        fi
+        echo ""
+        echo "[2] 检查网络连通性:"
+        if command -v ping >/dev/null 2>&1; then
+          ping -c 3 -W 5 center.javablade.com || echo "❌ ping 失败"
+        else
+          echo "⚠️  ping 命令不可用，跳过连通性测试"
+        fi
+        echo ""
+        echo "[3] 检查是否可以访问上游仓库（匿名测试）:"
+        if command -v git >/dev/null 2>&1; then
+          timeout 30 git ls-remote https://center.javablade.com/blade/BladeX-Tool.git HEAD || echo "❌ 无法访问仓库"
+        else
+          echo "⚠️  git 命令不可用"
+        fi
+        echo ""
+        echo "================================================================================"
+
     - name: 从配置文件中提取仓库并同步
       env:
         UPSTREAM_USERNAME: ${{ secrets.UPSTREAM_USERNAME }}