feat(ui): 重构端点健康状态为进度条可视化

- 将端点标签改为网格布局的进度条样式
- 显示 API 格式缩写和健康分数百分比
- 优化端点提示区分禁用、无可用密钥和未配置密钥状态
- 优化优先级管理对话框布局以显示更多内容
- 后端添加 total_keys 字段支持密钥状态区分

Closes #113

Co-authored-by: AAEE86 <ppk0227@hotmail.com>

src/api/admin/providers/summary.py

@@ -284,6 +284,7 @@ def _build_provider_summary(db: Session, provider: Provider) -> ProviderWithEndp
             "api_format": e.api_format,
             "health_score": endpoint_health_map.get(e.id, 1.0),
             "is_active": e.is_active,
+            "total_keys": len(keys_by_endpoint.get(e.id, [])),
             "active_keys": active_keys_by_endpoint.get(e.id, 0),
         }
         for e in endpoints