Fix UpdaterService class redefinition conflict

The MOC compiler was encountering two different definitions of UpdaterService:
1. A stub class in updater_dialog.h for non-Windows platforms
2. The real QObject-derived class in updater_service.h

Fixed by:
- Making updater_service.h include conditional in main.cpp (#ifdef _WIN32)
- Wrapping all UpdaterService usage in main.cpp with #ifdef _WIN32 blocks
- Adding clarifying comment to stub class in updater_dialog.h

This resolves the MOC compilation errors and ensures the updater
functionality is only available on Windows as intended.

src/citron/main.cpp

@@ -166,8 +166,8 @@ static FileSys::VirtualFile VfsDirectoryCreateFileWrapper(const FileSys::Virtual
 #include "citron/uisettings.h"
 #ifdef _WIN32
 #include "citron/updater/updater_dialog.h"
-#endif
 #include "citron/updater/updater_service.h"
+#endif
 #include "citron/util/clickable_label.h"
 #include "citron/util/performance_overlay.h"
 #include "citron/util/vram_overlay.h"
@@ -5522,6 +5522,7 @@ int main(int argc, char* argv[]) {
 
     QApplication app(argc, argv);
 
+#ifdef _WIN32
     // Check for and apply staged updates before starting the main application
     std::filesystem::path app_dir = std::filesystem::path(QCoreApplication::applicationDirPath().toStdString());
     if (Updater::UpdaterService::HasStagedUpdate(app_dir)) {
@@ -5531,6 +5532,7 @@ int main(int argc, char* argv[]) {
                                    QObject::tr("Citron has been updated successfully!"));
         }
     }
+#endif
 
 #ifdef _WIN32
     OverrideWindowsFont();
@@ -5581,6 +5583,7 @@ void GMainWindow::OnCheckForUpdates() {
 }
 
 void GMainWindow::CheckForUpdatesAutomatically() {
+#ifdef _WIN32
     // Check if automatic updates are enabled
     if (!Settings::values.enable_auto_update_check.GetValue()) {
         return;
@@ -5620,6 +5623,7 @@ void GMainWindow::CheckForUpdatesAutomatically() {
 
     // Start the silent update check
     updater_service->CheckForUpdates(update_url);
+#endif
 }
 
 void GMainWindow::OnToggleGridView() {

src/citron/updater/updater_dialog.h

@@ -18,6 +18,7 @@
 // Forward declarations for non-Windows platforms
 namespace Updater {
 struct UpdateInfo;
+// Stub class for non-Windows platforms - not a QObject
 class UpdaterService {
 public:
     enum class UpdateResult {