fix: add missing destructor definitions in .cpp files

- Added destructor definitions (= default) to all classes that had them declared in header but not defined
- Fixes 'undefined reference to destructor' linker errors across 30+ classes
- Covers services, UI components, and synchronizers

src/ui/connectionwizard.cpp

@@ -220,4 +220,4 @@ void ConnectionWizard::accept()
     emit settingsReady(settings);
     QWizard::accept();
 }
-
+ConnectionWizard::~ConnectionWizard() = default;