Added small system overview

Moonlight.Api/Services/ApplicationService.cs

@@ -0,0 +1,64 @@
+using System.Diagnostics;
+using Microsoft.Extensions.Hosting;
+using Moonlight.Api.Helpers;
+
+namespace Moonlight.Api.Services;
+
+public class ApplicationService : IHostedLifecycleService
+{
+    public DateTimeOffset StartedAt { get; private set; }
+    public string VersionName { get; private set; } = "N/A";
+    public bool IsUpToDate { get; set; } = true;
+    public string OperatingSystem { get; private set; } = "N/A";
+    
+    public Task<long> GetMemoryUsageAsync()
+    {
+        using var currentProcess = Process.GetCurrentProcess();
+        return Task.FromResult(currentProcess.WorkingSet64);
+    }
+    
+    public async Task<double> GetCpuUsageAsync()
+    {
+        using var currentProcess = Process.GetCurrentProcess();
+        
+        // Get initial values
+        var startCpuTime = currentProcess.TotalProcessorTime;
+        var startTime = DateTime.UtcNow;
+
+        // Wait a bit to calculate the diff
+        await Task.Delay(500);
+
+        // New values
+        var endCpuTime = currentProcess.TotalProcessorTime;
+        var endTime = DateTime.UtcNow;
+
+        // Calculate CPU usage
+        var cpuUsedMs = (endCpuTime - startCpuTime).TotalMilliseconds;
+        var totalMsPassed = (endTime - startTime).TotalMilliseconds;
+        var cpuUsagePercent = (cpuUsedMs / (Environment.ProcessorCount * totalMsPassed)) * 100;
+
+        return Math.Round(cpuUsagePercent, 2);
+    }
+    
+    public async Task StartedAsync(CancellationToken cancellationToken)
+    {
+        StartedAt = DateTimeOffset.UtcNow;
+        
+        // TODO: Update / version check
+
+        VersionName = "v2.1.0 (a2d4edc0e5)";
+        IsUpToDate = true;
+
+        OperatingSystem = OsHelper.GetName();
+    }
+
+    #region Unused
+
+    public Task StartAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+    public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+    public Task StartingAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+    public Task StoppedAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+    public Task StoppingAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+
+    #endregion
+}