feat: daily node restart controlled from the admin, connect timings as a default line task [CI]

Agents and Probes exit in order at a configured time (default 04:30 UTC+8, switch and time zone in the admin settings) and the service manager starts them again; a local restart_at or MOSHIRO_RESTART_AT wins. The connect kind (TCP connect and TLS handshake timings) is now a default continuous line template, with a section on the line page.

backend/fleet/src/Fleet.Hosting/Hosting.cs

@@ -126,7 +126,8 @@ public static class PlatformCheck
 /// <summary>处理 Ctrl+C 和 SIGTERM：取消令牌，让各个模块有序退出。</summary>
 public static class ServiceShell
 {
-    public static async Task RunAsync(Func<CancellationToken, Task> run, INodeLog log)
+    /// <param name="restart">每天定时有序退出一次（见 <see cref="RestartController"/>），重新拉起由服务管理器负责。</param>
+    public static async Task RunAsync(Func<CancellationToken, Task> run, INodeLog log, RestartController? restart = null, TimeProvider? time = null)
     {
         using var cts = new CancellationTokenSource();
         using PosixSignalRegistration term = PosixSignalRegistration.Create(PosixSignal.SIGTERM, context =>
@@ -156,6 +157,7 @@ public static class ServiceShell
             cts.Cancel();
         });
         Task trimmer = TrimHeapAsync(cts.Token);
+        Task scheduled = restart is null ? Task.CompletedTask : WaitForRestartAsync(restart, time ?? TimeProvider.System, log, cts);
         try
         {
             await run(cts.Token);
@@ -168,6 +170,38 @@ public static class ServiceShell
         {
             await cts.CancelAsync();
             await trimmer;
+            await scheduled;
+        }
+    }
+
+    private static async Task WaitForRestartAsync(RestartController restart, TimeProvider time, INodeLog log, CancellationTokenSource cts)
+    {
+        while (!cts.IsCancellationRequested)
+        {
+            // 先取令牌、再取设置：中间被改动的话令牌会被取消，下一轮重新排
+            CancellationToken changed = restart.ChangeToken;
+            RestartSchedule? schedule = restart.Current;
+            using CancellationTokenSource wait = CancellationTokenSource.CreateLinkedTokenSource(cts.Token, changed);
+            try
+            {
+                if (schedule is null)
+                {
+                    await Task.Delay(Timeout.Infinite, wait.Token);
+                    continue;
+                }
+
+                DateTimeOffset next = schedule.NextAfter(time.GetUtcNow() + RestartSchedule.MinimumUptime);
+                log.Info("restart scheduled", ("at", next.ToString("O", System.Globalization.CultureInfo.InvariantCulture)), ("source", restart.IsLocal ? "local" : "panel"));
+                await Task.Delay(next - time.GetUtcNow(), time, wait.Token);
+            }
+            catch (OperationCanceledException)
+            {
+                continue; // 进程在退出，或者设置被改了：循环条件和下一轮会处理
+            }
+
+            log.Info("stopping", ("result", "scheduled_restart"));
+            await cts.CancelAsync();
+            return;
         }
     }