refactor: improve connection handling and file service logic

- remove handleTokenCheck
- rename /chenk_token to /ping
- replace file_selector with file_picker on Android
- rename ChatServer back to ChatService
- simplify FileService port handling
- fix device connection and JoinMessage logic
- support mouse back navigation
- request Android file management permission

Author: Laurie-Lin

android/app/src/main/AndroidManifest.xml

@@ -1,7 +1,10 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
     package="com.nightmare.fastshare">
 
     <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE"
+        tools:ignore="AllFilesAccessPolicy,ScopedStorage" />
     <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
     <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />

lib/common/config.dart

@@ -3,9 +3,6 @@ class Config {
   // 下面两个端口是单个文件部署用到的端口
   static int shelfPortRangeStart = 13000;
   static int shelfPortRangeEnd = 13010;
-  // 下面两个端口是文件服务器用到的端口，主要用来web上传文件到客户端
-  static int filePortRangeStart = 13010;
-  static int filePortRangeEnd = 13020;
   // 下面两个是聊天服务器的端口
   static int chatPortRangeStart = 12000;
   static int chatPortRangeEnd = 12010;

lib/common/device.dart

@@ -0,0 +1,60 @@
+import 'device_type.dart';
+
+class Device {
+  Device(
+    this.id, {
+    this.deviceType,
+    this.deviceName,
+    this.url,
+    this.messagePort,
+  });
+  String? id;
+  DeviceType? deviceType;
+  String? deviceName;
+  // url prefix
+  String? url;
+  int? messagePort;
+  bool isAlive = true;
+
+  /// 当一个新的设备连接到当前设备的时候，需要回一个连接消息。
+  ///
+  /// 用来处理 UDP 广播只有 A -> B，没有 B -> A 的情况，
+  /// 导致 A 的连接列表没有 B。
+  ///
+  /// 这个在设备心跳包没有收到的情况下，会再次置为 false。
+  ///
+  /// 保证：
+  /// A 启动 -> B 启动 -> A 连过 B -> A 关闭 -> A 再打开
+  /// 即使只有 B 连过 A，B 依然会主动给 A 发送连接消息。
+  ///
+  /// When a new device connects to the current device, a connection message needs to be sent back.
+  ///
+  /// This is used to handle the situation where there is only A -> B in UDP broadcast, and no B -> A, which leads to A's connection list not having B.
+  /// This will be set to false again when the device heartbeat is not received.
+  ///
+  /// Ensure:
+  /// A starts -> B starts -> A connects to B -> A closes -> A opens again
+  /// Even if only B connects to A, B will still actively send a connection message to A.
+  bool sendedJoinMessage = false;
+
+  /// 防止重复发送，因为时序的问题，A 可能会收到两次 B 的 JoinMessage
+  ///
+  /// Prevent duplicate sending, because of the timing issue, A may receive B's JoinMessage twice.
+  bool sendedHistoryMessage = false;
+
+  @override
+  int get hashCode => id.hashCode;
+
+  @override
+  bool operator ==(Object other) {
+    if (other is Device) {
+      return id == other.id;
+    }
+    return false;
+  }
+
+  @override
+  String toString() {
+    return 'id:$id deviceType:$deviceType deviceName:$deviceName address:$url';
+  }
+}