Implement serialization/deserialization and persistent storage across services

- Add serialize/deserialize support for core models
- Add file-based load/save functions in management services
- Introduce FileManager, Config, Utility and helper utilities
- Persist observer IDs for notification services
- Resolve object relationships during load (services, bookings, invoices, job cards)
- Add controller-level loadSystemData/saveSystemData
- Load data at app startup and save on shutdown

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/utilities/InputHelper.h

@@ -34,7 +34,7 @@ namespace util
 
     /*
      * Function: read
-     * Description: Reads a line of text input from console into a string.
+     * Description: Reads a line of text input from console into a string and cleans it up.
      * Parameters:
      *     value - reference to a string where the input will be stored
      * Returns:
@@ -43,6 +43,15 @@ namespace util
     inline void read(std::string& value)
     {
         std::getline(std::cin >> std::ws, value);
+        std::string cleanedValue;
+        for (int index = 0; index < value.length(); index++)
+        {
+            if (value[index] != ',')
+            {
+                cleanedValue += value[index];
+            }
+        }
+        value = cleanedValue;
     }
 
     /*