fix: System.ObjectDisposedException for db context into sync secrvice

Endpoint/Controllers/V1/Configuration/ScheduleController.cs

@@ -2,6 +2,7 @@
 using Cronos;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
@@ -191,15 +192,20 @@ public class ScheduleController(ILogger<ScheduleController> logger, IOptionsSnap
             filePaths.Add((filePath, defaultCampus[i]));
         }
 
-        var sync = (ScheduleSynchronizer)ActivatorUtilities.GetServiceOrCreateInstance(provider, typeof(ScheduleSynchronizer));
-
         if (force)
         {
-            dbContext.Lessons.RemoveRange(dbContext.Lessons.ToList());
+            dbContext.Lessons.RemoveRange(await dbContext.Lessons.ToListAsync());
             await dbContext.SaveChangesAsync();
         }
 
-        _ = sync.StartSync(filePaths, CancellationToken.None);
+        var scopeFactory = provider.GetRequiredService<IServiceScopeFactory>();
+        _ = Task.Run(async () =>
+        {
+            using var scope = scopeFactory.CreateScope();
+            var sync = scope.ServiceProvider.GetRequiredService<ScheduleSynchronizer>();
+
+            await sync.StartSync(filePaths, CancellationToken.None);
+        }, CancellationToken.None);
 
         return Ok();
     }