Fix architectural and functional issues in PocketMC

- Deleted empty scaffolding UnitTest1.cs files in test projects to clean up tests
- Ensured RCON 'save-all' during backups fully awaits via 'save-all flush' and explicitly verified return messages to avoid world corruption
- Secured RemoteDashboardHost by adding CORS and an anti-CSRF check requiring an X-Requested-With header on POST requests
- Enforced a hard memory cap of 5000 lines on console output history to prevent OOM
- Optimized ResourceMonitorService polling to gracefully back off to 10s intervals when the application window is minimized
- Added X-Requested-With header to integration tests to bypass Anti-CSRF successfully

Author: sizwinz

PocketMC.Desktop.Tests/RemoteControlApiIntegrationTests.cs

@@ -65,6 +65,7 @@ public RemoteControlApiIntegrationTests()
         {
             BaseAddress = new Uri($"http://127.0.0.1:{_port}")
         };
+        _client.DefaultRequestHeaders.Add("X-Requested-With", "XMLHttpRequest");
     }
 
     public async Task InitializeAsync()