feat(launcher): SimpleLite 进程独立化与 DLL 热更新

- FollowParent=false 时在 Windows 用 cmd /c start 脱离父进程组，关闭 MiGu.Server 不再连带结束 SimpleLite
- 新增 SimpleLiteBuildSync：SimpleLite 未运行时把 obj/Debug 最新 DLL 同步到 bin/Debug，并探测「前往站点」API 是否可用
- 新增 RestartForUpdate 与 POST /api/health/simplelite/restart-for-update：一键关闭、同步、重启以加载新 API
- 诊断增加 FollowParent / GotoSiteApiAvailable / DeployHint；新增 scripts/redeploy-simplelite.ps1 部署脚本
- Dispose 增加 _disposed 幂等保护，避免重复释放

MiGu.Server/Controllers/HealthController.cs

@@ -1,4 +1,5 @@
-using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
 using MiGu.Server.Launcher;
 
 namespace MiGu.Server.Controllers;
@@ -39,4 +40,16 @@ public class HealthController : ControllerBase
     /// </summary>
     [HttpGet("simplelite")]
     public IActionResult GetSimpleLiteDiagnostics() => Ok(_launcher.GetDiagnostics());
+
+    /// <summary>
+    /// 关闭 SimpleLite、同步最新 DLL、重新拉起。用于「前往站点」API 缺失时一键更新。
+    /// </summary>
+    [HttpPost("simplelite/restart-for-update")]
+    [Authorize]
+    public IActionResult RestartSimpleLiteForUpdate([FromQuery] string launchMode = "webonly")
+    {
+        var result = _launcher.RestartForUpdate(launchMode);
+        var diag = _launcher.GetDiagnostics();
+        return Ok(new { restart = result, diagnostics = diag });
+    }
 }