refactor(chat-ui): 移除HeaderContainer和SendButton，添加装饰图片，修复Enter键监听

- 删除 HeaderContainer 和 StatusLabel（状态显示）
- 删除 SendButton（发送按钮）
- 添加聊天框背景图和装饰图片
- 设置 TextureRect modulate 为白色，修复黑框问题
- 移除 ChatPanel 背景色，使背景透明
- 修复 is_key_pressed 错误，改用 InputEventKey 类型检查
- 移除 _update_connection_status 函数及相关调用

scenes/ui/ChatUI.tscn

@@ -1,9 +1,13 @@
-[gd_scene load_steps=3 format=3 uid="uid://bv7k2nan4xj8q"]
+[gd_scene load_steps=6 format=3 uid="uid://bv7k2nan4xj8q"]
 
 [ext_resource type="Script" uid="uid://pibdlvhb12q8" path="res://scenes/ui/ChatUI.gd" id="1"]
 [ext_resource type="Texture2D" uid="uid://flepo0gpb55h" path="res://assets/ui/chat/缩略框背景.png" id="2_7dhmv"]
+[ext_resource type="Texture2D" uid="uid://clmgyxpeh5742" path="res://assets/ui/chat/输入框背景.png" id="3_fbft8"]
+[ext_resource type="Texture2D" uid="uid://q0ijn5y0tbw3" path="res://assets/ui/chat/装饰2.png" id="4_xo31h"]
+[ext_resource type="Texture2D" uid="uid://ct0cl4h2i6ydn" path="res://assets/ui/chat/装饰.png" id="5_xlxdo"]
 
 [node name="ChatUI" type="Control"]
+unique_name_in_owner = true
 custom_minimum_size = Vector2(10, 20)
 layout_mode = 3
 anchors_preset = 15
@@ -12,18 +16,8 @@ anchor_bottom = 1.0
 grow_horizontal = 2
 grow_vertical = 2
 mouse_filter = 2
-unique_name_in_owner = true
 script = ExtResource("1")
 
-[node name="TextureRect" type="TextureRect" parent="."]
-layout_mode = 0
-offset_left = 10.0
-offset_top = 358.0
-offset_right = 460.0
-offset_bottom = 758.0
-texture = ExtResource("2_7dhmv")
-expand_mode = 1
-
 [node name="ChatPanel" type="Panel" parent="."]
 unique_name_in_owner = true
 layout_mode = 1
@@ -35,6 +29,15 @@ offset_top = -410.0
 offset_right = 460.0
 offset_bottom = -10.0
 grow_vertical = 0
+theme_override_styles/panel = null
+
+[node name="TextureRect" type="TextureRect" parent="ChatPanel"]
+layout_mode = 0
+offset_right = 450.0
+offset_bottom = 400.0
+texture = ExtResource("2_7dhmv")
+expand_mode = 1
+modulate = Color(1, 1, 1, 1)
 
 [node name="VBoxContainer" type="VBoxContainer" parent="ChatPanel"]
 layout_mode = 1
@@ -49,17 +52,6 @@ grow_horizontal = 2
 grow_vertical = 2
 theme_override_constants/separation = 8
 
-[node name="HeaderContainer" type="HBoxContainer" parent="ChatPanel/VBoxContainer"]
-layout_mode = 2
-
-[node name="StatusLabel" type="Label" parent="ChatPanel/VBoxContainer/HeaderContainer"]
-unique_name_in_owner = true
-layout_mode = 2
-size_flags_horizontal = 3
-theme_override_colors/font_color = Color(0.5, 0.5, 0.5, 1)
-theme_override_font_sizes/font_size = 12
-text = "○ 未连接"
-
 [node name="ChatHistory" type="ScrollContainer" parent="ChatPanel/VBoxContainer"]
 unique_name_in_owner = true
 layout_mode = 2
@@ -82,7 +74,30 @@ layout_mode = 2
 size_flags_horizontal = 3
 placeholder_text = "输入消息..."
 
-[node name="SendButton" type="Button" parent="ChatPanel/VBoxContainer/InputContainer"]
-unique_name_in_owner = true
-layout_mode = 2
-text = "发送"
+[node name="TextureRect" type="TextureRect" parent="ChatPanel/VBoxContainer/InputContainer/ChatInput"]
+layout_mode = 0
+offset_right = 435.0
+offset_bottom = 30.0
+texture = ExtResource("3_fbft8")
+expand_mode = 1
+modulate = Color(1, 1, 1, 1)
+
+[node name="TextureRect2" type="TextureRect" parent="ChatPanel"]
+layout_mode = 0
+offset_left = 10.0
+offset_top = 10.0
+offset_right = 20.0
+offset_bottom = 20.0
+texture = ExtResource("4_xo31h")
+expand_mode = 1
+modulate = Color(1, 1, 1, 1)
+
+[node name="TextureRect3" type="TextureRect" parent="ChatPanel"]
+layout_mode = 0
+offset_left = 430.0
+offset_top = 340.0
+offset_right = 440.0
+offset_bottom = 350.0
+texture = ExtResource("5_xlxdo")
+expand_mode = 1
+modulate = Color(1, 1, 1, 1)