弟子面板与信息面板初步搭建，新增管理面板样式

- 新增 DisciplePanel/DiscipleInformationPanel 场景（src/UI/Panels/Manager/ 下）
- MainGame.tscn 接入管理面板入口
- 新增 manager_style_box_flat 样式资源

resources/disciple_info_label_settings.tres

@@ -8,3 +8,4 @@ paragraph_spacing = 1.0
 font = ExtResource("1_f7lwv")
 font_size = 24
 font_color = Color(0, 0, 0, 1)
+shadow_color = Color(0.9128214, 0.63396364, 0.6629118, 1)

resources/manager_style_box_flat.tres

@@ -0,0 +1,9 @@
+[gd_resource type="StyleBoxFlat" format=3 uid="uid://e86yw57h4v2s"]
+
+[resource]
+bg_color = Color(0.34372595, 0.630709, 0.8494593, 1)
+border_width_left = 80
+border_width_top = 40
+border_width_right = 80
+border_width_bottom = 40
+border_color = Color(0.8, 0.8, 0.8, 0)