Implemented system overview

Moonlight.ApiServer/Http/Controllers/Admin/Sys/SystemController.cs

@@ -0,0 +1,38 @@
+using Microsoft.AspNetCore.Mvc;
+using MoonCore.Attributes;
+using Moonlight.ApiServer.Services;
+using Moonlight.Shared.Http.Responses.Admin.Sys;
+
+namespace Moonlight.ApiServer.Http.Controllers.Admin.Sys;
+
+[ApiController]
+[Route("api/admin/system")]
+public class SystemController : Controller
+{
+    private readonly ApplicationService ApplicationService;
+
+    public SystemController(ApplicationService applicationService)
+    {
+        ApplicationService = applicationService;
+    }
+
+    [HttpGet]
+    [RequirePermission("admin.system.overview")]
+    public async Task<SystemOverviewResponse> GetOverview()
+    {
+        return new()
+        {
+            Uptime = await ApplicationService.GetUptime(),
+            CpuUsage = await ApplicationService.GetCpuUsage(),
+            MemoryUsage = await ApplicationService.GetMemoryUsage(),
+            OperatingSystem = await ApplicationService.GetOsName()
+        };
+    }
+
+    [HttpPost("shutdown")]
+    [RequirePermission("admin.system.shutdown")]
+    public async Task Shutdown()
+    {
+        await ApplicationService.Shutdown();
+    }
+}