feat(hub): add ServerChan task notifications (#515)

* fix(hub): 修复发送后状态显示延迟

* feat(hub): 接入Server酱任务通知

* fix(hub): 仅在会话结束时发送完成通知

* fix(hub): avoid reviving inactive queued sessions

* fix(hub): address notification review feedback

* fix(hub): expire queued thinking on hub clock

* fix(hub): 修复任务通知 review 反馈

hub/src/sync/syncEngine.ts

@@ -214,8 +214,13 @@ export class SyncEngine {
         this.triggerDedupIfNeeded(payload.sid)
     }
 
-    handleSessionEnd(payload: { sid: string; time: number }): void {
+    handleSessionEnd(payload: { sid: string; time: number; reason?: 'completed' | 'terminated' | 'error' }): void {
         this.sessionCache.handleSessionEnd(payload)
+        this.eventPublisher.emit({
+            type: 'session-ended',
+            sessionId: payload.sid,
+            reason: payload.reason
+        })
         // Retry dedup now that this session is inactive — a prior dedup may have
         // skipped it because it was still active at the time.
         this.triggerDedupIfNeeded(payload.sid)
@@ -285,6 +290,7 @@ export class SyncEngine {
         }
     ): Promise<void> {
         await this.messageService.sendMessage(sessionId, payload)
+        this.sessionCache.markMessageQueued(sessionId)
     }
 
     async approvePermission(