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/rulesmanagerdialog.cpp

@@ -295,4 +295,5 @@ void RulesManagerDialog::onImportExport(bool import)
 void RulesManagerDialog::refresh()
 {
     loadRules();
-}
+}
+RulesManagerDialog::~RulesManagerDialog() = default;