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/agent/src/MoShiro.Agent/AgentConfig.cs

@@ -22,6 +22,10 @@ public sealed class AgentConfig
 
     [JsonPropertyName("reporting")]
     public ReportingSection Reporting { get; set; } = new();
+
+    /// <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。</summary>
+    [JsonPropertyName("restart_at")]
+    public string? RestartAt { get; set; }
 }
 
 public sealed class ReportingSection