mobile: 提交 android/ios 平台脚手架与打包配置（B-58）

- flutter create 生成的 android/ ios/ 脚手架入库，服务器/使用者无需再装 Flutter
- AndroidManifest：补 INTERNET/录音/存储权限，应用名改「畅联」，开 usesCleartextTraffic（内网 http/ws）
- iOS Info.plist：麦克风/相册用途说明、ATS 放行内网明文、显示名「畅联」
- gradle：阿里云镜像优先（本网络 maven.google.com 不可达）；统一 Java/Kotlin 编译目标 17；
  抬升 livekit_client compileSdk 到 36 以满足 flutter_webrtc 的 AAR 校验
- README 更新为「直接打包」流程

mobile/ios/Runner.xcodeproj/project.xcworkspace/contents.xcworkspacedata

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Workspace
+   version = "1.0">
+   <FileRef
+      location = "self:">
+   </FileRef>
+</Workspace>

mobile/ios/Runner.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>

mobile/ios/Runner.xcodeproj/project.xcworkspace/xcshareddata/WorkspaceSettings.xcsettings

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>PreviewsEnabled</key>
+	<false/>
+</dict>
+</plist>