feat: 新增工作台模式、系统托盘，修复多平台兼容性问题

1. 新增工作台三栏布局模式，适配宽屏设备
2. 添加跨平台系统托盘支持，新增托盘图标资源
3. 修复工作台模式下导航返回异常问题
4. 统一JSON类型安全解析，替换硬类型转换
5. 增加macOS深度链接支持，统一渠道分发信息
6. 优化部分页面生命周期和状态加载逻辑
7. 移除废弃的nearby_connections依赖

lib/features/file_transfer/models/cloud_cache_record.dart

@@ -1,11 +1,13 @@
 // ============================================================
 // 闲言APP — 云端暂存记录模型
 // 创建时间: 2026-05-12
-// 更新时间: 2026-05-12
+// 更新时间: 2026-06-19
 // 作用: 云端暂存文件记录 — 上传/下载/过期/加密状态管理
-// 上次更新: v11.1.0 初始版本
+// 上次更新: 类型安全修复(int vs num): fromJson 时间戳使用 SafeJson.parseInt
 // ============================================================
 
+import 'package:xianyan/core/utils/safe_json.dart';
+
 enum CloudCacheUploadStatus {
   pending('pending', '待上传', '⏳'),
   encrypting('encrypting', '加密中', '🔐'),
@@ -193,21 +195,21 @@ class CloudCacheRecord {
         json['downloadStatus'] as String? ?? 'none',
       ),
       expiresAt: json['expiresAt'] != null
-          ? DateTime.fromMillisecondsSinceEpoch(json['expiresAt'] as int)
+          ? DateTime.fromMillisecondsSinceEpoch(SafeJson.parseInt(json['expiresAt']))
           : null,
       uploadedAt: json['uploadedAt'] != null
-          ? DateTime.fromMillisecondsSinceEpoch(json['uploadedAt'] as int)
+          ? DateTime.fromMillisecondsSinceEpoch(SafeJson.parseInt(json['uploadedAt']))
           : null,
       downloadedAt: json['downloadedAt'] != null
-          ? DateTime.fromMillisecondsSinceEpoch(json['downloadedAt'] as int)
+          ? DateTime.fromMillisecondsSinceEpoch(SafeJson.parseInt(json['downloadedAt']))
           : null,
       ownerId: json['ownerId'] as String? ?? '',
       targetId: json['targetId'] as String?,
       createdAt: json['createdAt'] != null
-          ? DateTime.fromMillisecondsSinceEpoch(json['createdAt'] as int)
+          ? DateTime.fromMillisecondsSinceEpoch(SafeJson.parseInt(json['createdAt']))
           : DateTime.now(),
       updatedAt: json['updatedAt'] != null
-          ? DateTime.fromMillisecondsSinceEpoch(json['updatedAt'] as int)
+          ? DateTime.fromMillisecondsSinceEpoch(SafeJson.parseInt(json['updatedAt']))
           : null,
     );
   }

lib/features/file_transfer/models/transfer_task.dart

@@ -1,11 +1,12 @@
 // ============================================================
 // 闲言APP — 传输任务模型
 // 创建时间: 2026-05-09
-// 更新时间: 2026-05-12
+// 更新时间: 2026-06-19
 // 作用: 文件传输助手传输任务数据模型 — 进度/速度/状态/校验/断点续传
-// 上次更新: v11.0.0 新增断点续传字段(fileId/totalChunks/receivedChunks/retryCount等)
+// 上次更新: 类型安全修复(int vs num): receivedChunks 列表元素使用 SafeJson.parseInt
 // ============================================================
 
+import 'package:xianyan/core/utils/safe_json.dart';
 import 'transfer_enums.dart';
 import 'transfer_device.dart';
 
@@ -288,7 +289,7 @@ class TransferTask {
       chunkSize: (json['chunkSize'] as num?)?.toInt() ?? 65536,
       totalChunks: (json['totalChunks'] as num?)?.toInt(),
       receivedChunks: (json['receivedChunks'] as List<dynamic>?)
-          ?.map((e) => e as int)
+          ?.map((e) => SafeJson.parseInt(e))
           .toSet(),
       retryCount: (json['retryCount'] as num?)?.toInt() ?? 0,
       maxRetries: (json['maxRetries'] as num?)?.toInt() ?? 3,