feat: WebGL打包配置 + UI页面系统完善

- WebGL Build: 全屏1920x1080，Build文件夹gitignore
- 导入Arial.ttf字体解决WebGL打包字体问题
- 修复PageController所有按钮绑定(BtnExamMode等)
- ModeSelectPanel添加ModeDesc描述文字
- 删除PageControllerEditor.cs(Editor脚本导致WebGL编译失败)
- 场景模型资源导入(Environment/playground)

ProjectSettings/ProjectSettings.asset

@@ -13,7 +13,7 @@ PlayerSettings:
   useOnDemandResources: 0
   accelerometerFrequency: 60
   companyName: DefaultCompany
-  productName: VFS
+  productName: "\u8FD0\u52A8\u4F24\u5BB3\u73B0\u573A\u6025\u6551\u865A\u62DF\u4EFF\u771F\u5B9E\u9A8C"
   defaultCursor: {fileID: 0}
   cursorHotspot: {x: 0, y: 0}
   m_SplashScreenBackgroundColor: {r: 0.13725491, g: 0.12156863, b: 0.1254902, a: 1}
@@ -44,8 +44,8 @@ PlayerSettings:
   m_HolographicTrackingLossScreen: {fileID: 0}
   defaultScreenWidth: 1024
   defaultScreenHeight: 768
-  defaultScreenWidthWeb: 960
-  defaultScreenHeightWeb: 600
+  defaultScreenWidthWeb: 1920
+  defaultScreenHeightWeb: 1080
   m_StereoRenderingPath: 0
   m_ActiveColorSpace: 1
   unsupportedMSAAFallback: 0