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/probe/src/MoShiro.Probe/ProbeConfig.cs

@@ -20,6 +20,10 @@ public sealed class ProbeFile
     [JsonPropertyName("server")]
     public string Server { get; set; } = "";
 
+    /// <summary>每天定时重启一次，例如 <c>04:00+08:00</c>（不写偏移按 UTC）；不写就不重启。环境变量 <c>MOSHIRO_RESTART_AT</c> 优先；这里是本地配置，从面板重新下载 probe.json 会丢掉它，所以容器里推荐用环境变量。</summary>
+    [JsonPropertyName("restart_at")]
+    public string? RestartAt { get; set; }
+
     [JsonPropertyName("limits")]
     public ProbeLimits Limits { get; set; } = new();
 }