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/tests/MoShiro.Backend.Tests/BackendFixture.cs

@@ -10,6 +10,12 @@ using MoShiro.TestSupport;
 
 namespace MoShiro.Backend.Tests;
 
+/// <summary>首次启动种入的默认线路任务模板数：udp_echo、tcp_echo、connect。</summary>
+internal static class Defaults
+{
+    public const int TaskCount = 3;
+}
+
 /// <summary>
 /// 在真实的 Kestrel 端口上启动整个后端（真实的 SQLite 与段文件，只是用临时目录和较快的轮询），
 /// 并提供管理员客户端（Bearer 令牌）和假 Agent。