Add MainHUD gameplay UI, net handshake updates, and server maintenance mode.

Introduce UiManager/MainHUD prefab flow, strengthen GameNet/WsClient, and add AIServer maintenance endpoint support.

Co-authored-by: Cursor <cursoragent@cursor.com>

AIClient/Assets/HotUpdate/Scripts/Net/WsClient.cs

@@ -38,6 +38,7 @@ namespace HotUpdate.Net
         public event Action OnConnected;
         public event Action<string> OnDisconnected;
         public event Action<string> OnMessage;
+        public event Action<int> OnReconnecting;
 
         public bool AutoReconnect { get; set; } = true;
         public float KeepAliveSeconds { get; set; } = 20f;
@@ -50,6 +51,20 @@ namespace HotUpdate.Net
             _ = ConnectInternalAsync();
         }
 
+        /// <summary>立刻断开并重新连接（重置退避计数）。</summary>
+        public void ForceReconnect()
+        {
+            if (string.IsNullOrEmpty(_url)) return;
+            _manualClose = false;
+            AutoReconnect = true;
+            _reconnectAttempt = 0;
+            SafeCancel();
+            try { _ws?.Dispose(); } catch { /* ignore */ }
+            _ws = null;
+            State = WsState.Disconnected;
+            _ = ConnectInternalAsync();
+        }
+
         public void SendText(string text)
         {
             if (string.IsNullOrEmpty(text)) return;
@@ -119,6 +134,7 @@ namespace HotUpdate.Net
                     _reconnectAttempt++;
                     int delayMs = Math.Min(30000, 1000 * (1 << Math.Min(5, _reconnectAttempt)));
                     Debug.Log($"[WsClient] reconnect in {delayMs}ms attempt={_reconnectAttempt}");
+                    OnReconnecting?.Invoke(_reconnectAttempt);
                     try
                     {
                         await Task.Delay(delayMs, CancellationToken.None);