Add documentation headers across system modules

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/utilities/Utility.h

@@ -1,3 +1,13 @@
+/*
+File: ObserversHelper.h
+Description: Provides utility functions for loading and saving observers
+             in the notification management system. Ensures that observer
+             IDs are validated against existing users in the datastore
+             before attaching them to the notification service.
+Author: Trenser
+Date: 22-May-2026
+*/
+
 #pragma once
 #include "NotificationManagementService.h"
 #include "FileHelper.h"
@@ -5,6 +15,20 @@
 
 namespace util
 {
+    /*
+    Function: loadObservers
+    Description: Loads observer IDs from a file and attaches the corresponding users
+                 to the notification management service. Validates that each observer ID
+                 exists in the datastore before attaching.
+    Parameters:
+        - filePath: const std::string&, path to the file containing observer IDs
+        - service: NotificationManagementService*, pointer to the notification service
+        - dataStore: DataStore&, reference to the datastore containing users
+    Returns:
+        - void
+    Throws:
+        - std::runtime_error if an observer ID is invalid (not found in datastore)
+    */
     inline void loadObservers(const std::string& filePath, NotificationManagementService* service, DataStore& dataStore)
     {
         auto observerIDs = util::loadRecords(filePath);
@@ -21,6 +45,16 @@ namespace util
         }
     }
 
+    /*
+    Function: saveObservers
+    Description: Saves the current observer IDs from the notification management service
+                 to a file for persistence.
+    Parameters:
+        - filePath: const std::string&, path to the file where observer IDs will be saved
+        - service: NotificationManagementService*, pointer to the notification service
+    Returns:
+        - void
+    */
     inline void saveObservers(const std::string& filePath, NotificationManagementService* service)
     {
         auto observerIDs = service->getObserverIDs();