feat(models): 模型自动下载(我的·模型管理) + 断点续传 + 旁路导入

实现 spec(2026-05-29-model-download-design)的模型分发功能:
- ModelManifest: 硬编码功能文件清单 + base URL https://file.myv0.com/
- FileDownloader: URLSessionDataDelegate 分块写盘,HTTP Range 断点续传 + 大小校验
  (根因修复:URL.resourceValues 会缓存文件大小,续传时先读 offset 再读 finalSize
   会拿到下载前的陈旧值导致校验误判;改用 FileManager.attributesOfItem)
- ModelDownloadService: @MainActor @Observable 编排逐文件下载,聚合进度/速度,
  支持下载全部/暂停/重试,以及旁路文件导入
- ModelStore: 新增 fileURL/localBytes/isComplete(可注入清单)/importModel(补 VL)
- ModelManagementView: 分模型卡片(状态/进度/速度) + 下载全部/暂停
  + NWPathMonitor 蜂窝提示 + 从文件导入(离线兜底)
- MeView: 模型管理卡改 NavigationLink + 动态状态(已就绪/下载中/N就绪)

测试(Swift Testing): Manifest 清单/字节数、Store 路径/校验/导入、
DownloadState、FileDownloader(URLProtocol mock:下载/Range续传/大小校验)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

康康/Features/Me/MeView.swift

@@ -7,6 +7,8 @@ struct MeView: View {
     @Query private var reminders: [MetricReminder]
     @Query private var customMetrics: [CustomMonitorMetric]
 
+    @State private var downloadService = ModelDownloadService.shared
+
     private var profile: UserProfile? { profiles.first }
     private var enabledReminderCount: Int { reminders.filter(\.enabled).count }
 
@@ -17,9 +19,7 @@ struct MeView: View {
                     profileCard
                     remindersCard
                     customMetricsCard
-                    settingsCard(title: "模型管理",
-                                 detail: "未配置",
-                                 icon: "cpu")
+                    modelManagementCard
                     settingsCard(title: "Face ID 启动锁",
                                  detail: "关闭",
                                  icon: "faceid")
@@ -42,6 +42,7 @@ struct MeView: View {
                 if profiles.isEmpty {
                     _ = UserProfileStore.loadOrCreate(in: ctx)
                 }
+                downloadService.refreshStates()
             }
         }
     }
@@ -161,6 +162,23 @@ struct MeView: View {
         return "\(customMetrics.count) 项"
     }
 
+    private var modelManagementCard: some View {
+        NavigationLink {
+            ModelManagementView()
+        } label: {
+            settingsCard(title: "模型管理", detail: modelDetail, icon: "cpu")
+        }
+        .buttonStyle(.plain)
+    }
+
+    private var modelDetail: String {
+        let states = downloadService.states
+        if ModelKind.allCases.allSatisfy({ states[$0]?.phase == .ready }) { return "已就绪" }
+        if downloadService.isAnyDownloading { return "下载中…" }
+        let readyCount = ModelKind.allCases.filter { states[$0]?.phase == .ready }.count
+        return readyCount == 0 ? "未下载" : "\(readyCount)/\(ModelKind.allCases.count) 就绪"
+    }
+
     private func settingsCard(title: String, detail: String, icon: String) -> some View {
         HStack(spacing: 12) {
             ZStack {