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/android/app/src/main/AndroidManifest.xml

@@ -0,0 +1,55 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <!-- 网络（OpenIM / 登录 / LiveKit 都要） -->
+    <uses-permission android:name="android.permission.INTERNET"/>
+    <!-- 语音消息录音与语音通话 -->
+    <uses-permission android:name="android.permission.RECORD_AUDIO"/>
+    <uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS"/>
+    <!-- 发图片/文件：按系统版本适配存储权限 -->
+    <uses-permission android:name="android.permission.READ_MEDIA_IMAGES"/>
+    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" android:maxSdkVersion="32"/>
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" android:maxSdkVersion="28"/>
+    <application
+        android:label="畅联"
+        android:name="${applicationName}"
+        android:icon="@mipmap/ic_launcher"
+        android:usesCleartextTraffic="true">
+        <activity
+            android:name=".MainActivity"
+            android:exported="true"
+            android:launchMode="singleTop"
+            android:taskAffinity=""
+            android:theme="@style/LaunchTheme"
+            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
+            android:hardwareAccelerated="true"
+            android:windowSoftInputMode="adjustResize">
+            <!-- Specifies an Android theme to apply to this Activity as soon as
+                 the Android process has started. This theme is visible to the user
+                 while the Flutter UI initializes. After that, this theme continues
+                 to determine the Window background behind the Flutter UI. -->
+            <meta-data
+              android:name="io.flutter.embedding.android.NormalTheme"
+              android:resource="@style/NormalTheme"
+              />
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN"/>
+                <category android:name="android.intent.category.LAUNCHER"/>
+            </intent-filter>
+        </activity>
+        <!-- Don't delete the meta-data below.
+             This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
+        <meta-data
+            android:name="flutterEmbedding"
+            android:value="2" />
+    </application>
+    <!-- Required to query activities that can process text, see:
+         https://developer.android.com/training/package-visibility and
+         https://developer.android.com/reference/android/content/Intent#ACTION_PROCESS_TEXT.
+
+         In particular, this is used by the Flutter engine in io.flutter.plugin.text.ProcessTextPlugin. -->
+    <queries>
+        <intent>
+            <action android:name="android.intent.action.PROCESS_TEXT"/>
+            <data android:mimeType="text/plain"/>
+        </intent>
+    </queries>
+</manifest>