diag(client/macos): 抓 sing-box urltest 内核日志,定位探测为何失败

确认 urltest 为空是内核探测 100% 失败(传输/读取链路均正常)。本次注入 log.level=debug,
StatsCollector 新增 Log 命令客户端,抓取内核日志里 urltest/gstatic 相关行(失败原因:
DNS/连接/超时),塞进 stats 的 klog 字段经主 app 可读日志透出 —— 直接看到内核报错。

CURRENT_PROJECT_VERSION 51→52。

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

client/macos/Runner/StatsClient.swift

@@ -67,9 +67,9 @@ final class StatsClient: NSObject {
                 if self.diagTick % 5 == 0 {
                     let urls = (obj["urltestResults"] as? [[String: Any]]) ?? []
                     let pairs = urls.map { "\($0["tag"] ?? "?")=\($0["delayMs"] ?? -1)" }.joined(separator: ",")
-                    NSLog("[pangolin/stats] dl=%@ ul=%@ urltest[%d]=%@ diag=%@",
+                    NSLog("[pangolin/stats] dl=%@ ul=%@ urltest[%d]=%@ diag=%@ klog=%@",
                           "\(obj["downloadSpeed"] ?? 0)", "\(obj["uploadSpeed"] ?? 0)", urls.count, pairs,
-                          "\(obj["diag"] ?? "-")")
+                          "\(obj["diag"] ?? "-")", "\(obj["klog"] ?? "-")")
                 }
                 self.emit(obj)
             }