refactor(GUI): 群組切mode/套用速度改並發(asyncio.gather)，清per-drone client過期註解

- gui.py: _handle_group_mode_change 與 _on_engagement_apply_speed 由
  單一 async 函式內 for 迴圈逐台 await（序列化，最壞 N×timeout）改為
  asyncio.gather 並發，各自等各自 ACK；行為語意不變。
- communication.py: set_mode/arm_drone/set_speed 前 3 處過期註解
  「避免多機並行時的競態條件」更正為共用 client + target_sysid 路由
  （OOM 修復後已非 per-drone、無 per-drone 狀態）。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/GUI/communication.py

@@ -1163,7 +1163,8 @@ class DroneMonitor(Node):
             
             _log("INFO", f"[SET_MODE] {drone_id} -> {mode_name} (custom_mode={custom_mode})")
             
-            # 獲取或創建該 drone 專用的 client（避免多機並行時的競態條件）
+            # 取得共用 command_long client（OOM 修復後已非 per-drone，靠 request 的
+            # target_sysid 路由；drone_id 僅用於一次性 lazy fallback，無 per-drone 狀態）
             client = self.get_or_create_client(drone_id)
             if not client:
                 _log("ERROR", "[SET_MODE] CommandLongClient 無法初始化")
@@ -1246,7 +1247,8 @@ class DroneMonitor(Node):
             action_name = "解鎖" if arm else "上鎖"
             _log("INFO", f"[ARM] {drone_id} -> {action_name}")
             
-            # 獲取或創建該 drone 專用的 client（避免多機並行時的競態條件）
+            # 取得共用 command_long client（OOM 修復後已非 per-drone，靠 request 的
+            # target_sysid 路由；drone_id 僅用於一次性 lazy fallback，無 per-drone 狀態）
             client = self.get_or_create_client(drone_id)
             if not client:
                 _log("ERROR", "[ARM] CommandLongClient 無法初始化")
@@ -1283,7 +1285,8 @@ class DroneMonitor(Node):
             
             _log("INFO", f"[TAKEOFF] {drone_id} -> 起飛 (高度={altitude}m)")
             
-            # 獲取或創建該 drone 專用的 client（避免多機並行時的競態條件）
+            # 取得共用 command_long client（OOM 修復後已非 per-drone，靠 request 的
+            # target_sysid 路由；drone_id 僅用於一次性 lazy fallback，無 per-drone 狀態）
             client = self.get_or_create_client(drone_id)
             if not client:
                 _log("ERROR", "[TAKEOFF] CommandLongClient 無法初始化")

src/GUI/gui.py

@@ -1573,26 +1573,29 @@ class ControlStationUI(QMainWindow):
         _log("INFO", f"Group {group_id} 準備切換模式為 {mode}")
         self.statusBar().showMessage("正在切換模式", 1000)
         
-        # 使用 asyncio 執行（通過事件循環）
+        # 使用 asyncio 執行（通過事件循環）。
+        # 並發：每台各自 set_mode + 各自等自己的 ACK，用 gather 同時發，
+        # 避免逐台 await 造成序列化（最壞情況 N×timeout 一路卡著）。
+        async def _change_one(drone_id):
+            try:
+                result = await self.monitor.set_mode(drone_id, mode)
+                if result:
+                    msg = f"{drone_id} 切換成功"
+                    _log("INFO", msg)
+                else:
+                    msg = f"{drone_id} 切換失敗"
+                    _log("WARN", msg)
+                self.message_queue.put((msg, 2000))
+            except Exception as e:
+                msg = f"{drone_id} 錯誤: {str(e)}"
+                _log("ERROR", msg)
+                traceback.print_exc()
+                self.message_queue.put((msg, 2000))
+
         async def do_mode_changes_async():
-            for drone_id in group.selected_drone_ids:
+            await asyncio.gather(
-                try:
+                *(_change_one(did) for did in group.selected_drone_ids)
-                    result = await self.monitor.set_mode(drone_id, mode)
+            )
-                    
-                    if result:
-                        msg = f"{drone_id} 切換成功"
-                        _log("INFO", msg)
-                        self.message_queue.put((msg, 2000))
-                    else:
-                        msg = f"{drone_id} 切換失敗"
-                        _log("WARN", msg)
-                        self.message_queue.put((msg, 2000))
-                
-                except Exception as e:
-                    msg = f"{drone_id} 錯誤: {str(e)}"
-                    _log("ERROR", msg)
-                    traceback.print_exc()
-                    self.message_queue.put((msg, 2000))
 
         # 通過事件循環提交異步任務
         loop = asyncio.get_event_loop()
@@ -2584,17 +2587,18 @@ class ControlStationUI(QMainWindow):
         if hasattr(self, 'orchestrator'):
             self.orchestrator.friendly_speed = float(friendly_speed)
 
+        async def _apply_one(did, speed, label):
+            try:
+                await self.monitor.set_speed(did, speed)
+            except Exception as e:
+                _log("ERROR", f"[套用速度] {label} {did} 失敗: {e}")
+
         async def do_apply():
-            for did in friendly_ids:
+            # 並發：友機各自 + 敵機，用 gather 同時發，各自等各自 ACK
-                try:
+            tasks = [_apply_one(did, friendly_speed, "友機") for did in friendly_ids]
-                    await self.monitor.set_speed(did, friendly_speed)
-                except Exception as e:
-                    _log("ERROR", f"[套用速度] 友機 {did} 失敗: {e}")
             if enemy_id:
-                try:
+                tasks.append(_apply_one(enemy_id, enemy_speed, "敵機"))
-                    await self.monitor.set_speed(enemy_id, enemy_speed)
+            await asyncio.gather(*tasks)
-                except Exception as e:
-                    _log("ERROR", f"[套用速度] 敵機 {enemy_id} 失敗: {e}")
 
         asyncio.run_coroutine_threadsafe(do_apply(), asyncio.get_event_loop())
         self.statusBar().showMessage(