chore(desktop): Tauri 命令 @reserved 全量标注 — 88个无前端调用命令已标注

- 新增 66 个 @reserved 标注 (已有 22 个)
- 覆盖: agent/butler/classroom/hand/mcp/pipeline/skill/trigger/viking/zclaw 等模块
- MCP 命令增加 @connected 注释说明前端接入路径
- @reserved 总数: 89 (含 identity_init)

desktop/src-tauri/src/classroom_commands/chat.rs

@@ -47,6 +47,7 @@ pub struct ClassroomChatCmdRequest {
 // ---------------------------------------------------------------------------
 
 /// Send a message in the classroom chat and get multi-agent responses.
+// @reserved: classroom chat functionality
 // @connected
 #[tauri::command]
 pub async fn classroom_chat(