Finalize DI: drop transitional VM ctor; harden disposal

Remove the transitional MainWindowViewModel(AppSettings, IStartupTracer) constructor and the _ownsServices flag now that every caller resolves the view model from the container; the container owns and disposes the hardware monitor (driver unload), so the view model no longer disposes it. Make HardwareMonitorService.Dispose idempotent with a _disposed guard, and run provider disposal in a finally block in MainWindow_Closed so the ring0 driver is always unloaded on real exit even if an earlier teardown step throws.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

LibreHardwareMonitor.Windows.WinUI/Services/HardwareMonitorService.cs

@@ -28,6 +28,7 @@ public sealed class HardwareMonitorService : IHardwareMonitorService
     private readonly UpdateVisitor _updateVisitor = new();
     private readonly TreeRebuildCoalescer _treeRebuildCoalescer;
     private bool _isOpen;
+    private bool _disposed;
 
     public HardwareMonitorService(AppSettings settings)
     {
@@ -199,6 +200,11 @@ public sealed class HardwareMonitorService : IHardwareMonitorService
 
     public void Dispose()
     {
+        if (_disposed)
+            return;
+
+        _disposed = true;
+
         // Clear before closing so any tree-rebuild task still pending its delay bails instead of rebuilding from a
         // half-closed Computer.
         _isOpen = false;