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/web/handlers/extensions.rs

@@ -10,8 +10,8 @@ use typeshare::typeshare;
 
 use crate::error::{AppError, Result};
 use crate::extensions::{
-    EasytierConfig, EasytierInfo, ExtensionId, ExtensionInfo, ExtensionLogs,
-    ExtensionsStatus, GostcConfig, GostcInfo, TtydConfig, TtydInfo,
+    EasytierConfig, EasytierInfo, ExtensionId, ExtensionInfo, ExtensionLogs, ExtensionsStatus,
+    GostcConfig, GostcInfo, TtydConfig, TtydInfo,
 };
 use crate::state::AppState;
 
@@ -108,9 +108,7 @@ pub async fn stop_extension(
     let mgr = &state.extensions;
 
     // Stop the extension
-    mgr.stop(ext_id)
-        .await
-        .map_err(|e| AppError::Internal(e))?;
+    mgr.stop(ext_id).await.map_err(|e| AppError::Internal(e))?;
 
     // Return updated status
     Ok(Json(ExtensionInfo {