fix(client/macos): PacketTunnelProvider 改用 completion-handler 绕开 Swift 6.2 编译器崩溃

Swift 6.2.3 在为 async 重写的 startTunnel 生成 ObjC 桥接 thunk 时崩溃
(emitInjectLoadableEnum)。改用 completion-handler 形式(直接是 @objc 原型)
绕开。startTunnel/stopTunnel/handleAppMessage 三个 override 同步改。

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

client/macos/PacketTunnel/PacketTunnelProvider.swift

@@ -30,7 +30,11 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
     // App Group 共享容器:放 sing-box 工作目录(缓存/日志)。主 app 与扩展同路径。
     private static let appGroup = "group.com.pangolin.pangolin"
 
-    override func startTunnel(options: [String: NSObject]?) async throws {
+    // 用 completion-handler 形式(而非 async):Swift 6.2 编译器在为 async 重写
+    // 生成 ObjC 桥接 thunk 时会崩(emitInjectLoadableEnum),completion-handler 直接
+    // 就是 @objc 原型,绕开该 bug。成功调 completionHandler(nil),失败传 error。
+    override func startTunnel(options: [String: NSObject]?,
+                              completionHandler: @escaping (Error?) -> Void) {
         log.info("startTunnel")
 
         // 1) sing-box JSON:优先取 startVPNTunnel 下发的 options["configContent"],
@@ -42,15 +46,17 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
             configContent = (try? Self.readSharedConfig()) ?? ""
         }
         guard !configContent.isEmpty else {
-            throw NSError(domain: "pangolin.tunnel", code: 1,
-                          userInfo: [NSLocalizedDescriptionKey: "empty sing-box config"])
+            completionHandler(NSError(domain: "pangolin.tunnel", code: 1,
+                userInfo: [NSLocalizedDescriptionKey: "empty sing-box config"]))
+            return
         }
 
-        // 2) libbox 基础路径(全部落在 App Group 容器内,sysess 沙盒可写)。
+        // 2) libbox 基础路径(全部落在 App Group 容器内,扩展沙盒可写)。
         guard let base = FileManager.default
             .containerURL(forSecurityApplicationGroupIdentifier: Self.appGroup) else {
-            throw NSError(domain: "pangolin.tunnel", code: 2,
-                          userInfo: [NSLocalizedDescriptionKey: "no app group container"])
+            completionHandler(NSError(domain: "pangolin.tunnel", code: 2,
+                userInfo: [NSLocalizedDescriptionKey: "no app group container"]))
+            return
         }
         let work = base.appendingPathComponent("work", isDirectory: true)
         try? FileManager.default.createDirectory(at: work, withIntermediateDirectories: true)
@@ -62,36 +68,41 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
         setup.workingPath = work.path
         setup.tempPath = NSTemporaryDirectory()
         LibboxSetup(setup, &setupError)
-        if let setupError { throw setupError }
+        if let setupError { completionHandler(setupError); return }
 
         let platform = PangolinPlatformInterface(provider: self)
         self.platformInterface = platform
 
         var newError: NSError?
         guard let service = LibboxNewService(configContent, platform, &newError) else {
-            throw newError ?? NSError(domain: "pangolin.tunnel", code: 3)
+            completionHandler(newError ?? NSError(domain: "pangolin.tunnel", code: 3)); return
         }
         self.boxService = service
-        try service.start()
+        do { try service.start() } catch { completionHandler(error); return }
+        completionHandler(nil)   // 隧道已起
+        return
         ──────────────────────────────────────────────────────────────────── */
 
-        // 骨架占位:xcframework 接入前,startTunnel 直接抛错,避免静默假成功。
-        throw NSError(domain: "pangolin.tunnel", code: 99, userInfo: [
+        // 骨架占位:xcframework 接入前,直接回错,避免静默假成功。
+        completionHandler(NSError(domain: "pangolin.tunnel", code: 99, userInfo: [
             NSLocalizedDescriptionKey:
                 "Libbox 尚未接入(见 docs/p1-macos-system-extension.md 步骤 3)",
-        ])
+        ]))
     }
 
-    override func stopTunnel(with reason: NEProviderStopReason) async {
+    override func stopTunnel(with reason: NEProviderStopReason,
+                             completionHandler: @escaping () -> Void) {
         log.info("stopTunnel reason=\(reason.rawValue)")
         /* if let service = boxService as? LibboxBoxService { try? service.close() } */
         boxService = nil
         platformInterface = nil
+        completionHandler()
     }
 
     // 主 app 经 sendProviderMessage 下发的控制(切节点等);也可改走 libbox CommandServer。
-    override func handleAppMessage(_ messageData: Data) async -> Data? {
-        nil
+    override func handleAppMessage(_ messageData: Data,
+                                   completionHandler: ((Data?) -> Void)?) {
+        completionHandler?(nil)
     }
 
     private static func readSharedConfig() throws -> String {