feat(video): 事务化切换与前端统一编排，增强视频输入格式支持

- 后端：切换事务+transition_id，/stream/mode 返回 switching/transition_id 与实际 codec

- 事件：新增 mode_switching/mode_ready，config/webrtc_ready/mode_changed 关联事务

- 编码/格式：扩展 NV21/NV16/NV24/RGB/BGR 输入与转换链路，RKMPP direct input 优化

- 前端：useVideoSession 统一切换，失败回退真实切回 MJPEG，菜单格式同步修复

- 清理：useVideoStream 降级为 MJPEG-only

src/auth/mod.rs

@@ -1,9 +1,9 @@
+pub mod middleware;
 mod password;
 mod session;
 mod user;
-pub mod middleware;
 
+pub use middleware::{auth_middleware, require_admin, AuthLayer, SESSION_COOKIE};
 pub use password::{hash_password, verify_password};
 pub use session::{Session, SessionStore};
 pub use user::{User, UserStore};
-pub use middleware::{AuthLayer, SESSION_COOKIE, auth_middleware, require_admin};