Update controller methods and fix const issues

Changes:
- Added stub implementations for Controller.cpp methods
- Fixed const issue in UserInterface methods (run, login, registerCustomer, handleOperation)
- Changed return types to use const pointers for read-only objects
- Updated maps and vectors to return const object pointers
- Fixed some function parameter names and signatures for consistency

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/views/UserInterface.h

@@ -11,10 +11,10 @@ private:
     AdminMenu m_adminMenu;
     TechnicianMenu m_technicianMenu;
     CustomerMenu m_customerMenu;
-    bool handleOperation(int choice) const;
+    bool handleOperation(int choice);
 public:
     UserInterface() {}
-    void run() const;
-    void login() const;
-    void registerCustomer() const;
+    void run();
+    void login();
+    void registerCustomer();
 };