Merge branch 'develop' into develop-sm-authentication-management

User Story #1953
User Story #1954

**Changes**
- Refactored Notification model to use SerializedNotification for shared memory persistence.
- Removed notification ownership from the User model and stored notifications separately in the DataStore.
- Added notification state tracking to support soft deletion.
- Updated notification creation, retrieval, and deletion flows to use DataStore-managed notifications.
- Refactored observer persistence for Service, Payment, and Inventory Management services to use shared memory mappings.
- Removed file-based observer loading and saving logic.
- Updated notification services to persist notifications directly through the DataStore.
- Added observer load/save support in DataStore.
- Removed legacy FileManager and file-based notification persistence utilities.
- Simplified observer interfaces and removed unused observer ID persistence methods.
- Updated application startup and shutdown flow to use DataStore initialization and cleanup.

Related work items: #1953, #1954

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/AuthenticationManagementService.cpp

@@ -10,6 +10,8 @@ Date:19-May-2026
 #include <stdexcept>
 #include "AuthenticationManagementService.h"
 #include "User.h"
+#include "Utility.h"
+#include "DataStoreLockGuard.h"
 
 User* AuthenticationManagementService::m_authenticatedUser = nullptr;
 
@@ -24,11 +26,12 @@ Return type: bool - true if login successful, false otherwise
 */
 bool AuthenticationManagementService::login(const std::string& username, const std::string& password)
 {
-	util::Map<std::string, User*> users = m_dataStore.getUsers();
-	int usersMapSize = users.getSize();
-	for (int index = 0; index < usersMapSize; index++)
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedUserMap = m_dataStore.getUsers();
+	int trackedUserMapSize = trackedUserMap.getSize();
+	for (int index = 0; index < trackedUserMapSize; index++)
 	{
-		User* user = users.getValueAt(index);
+		User* user = trackedUserMap.getValueAt(index).data;
 		if (username == user->getUserName())
 		{
 			if (password == user->getPassword())
@@ -74,9 +77,18 @@ Return type: void
 */
 void AuthenticationManagementService::changePassword(const std::string& newPassword)
 {
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedUsersMap = m_dataStore.getUsers();
 	if (m_authenticatedUser == nullptr)
 	{
 		throw std::runtime_error("There is no user currently logged in!");
 	}
+	int index = trackedUsersMap.find(m_authenticatedUser->getId());
+	if (index == -1)
+	{
+		throw std::runtime_error("User does not exist!\n");
+	}
 	m_authenticatedUser->setPassword(newPassword);
+	trackedUsersMap.getValueAt(index).state = RecordState::MODIFIED;
+	m_dataStore.saveUsers();
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/UserManagementService.cpp

@@ -180,7 +180,6 @@ util::Vector<Notification*> UserManagementService::getUserNotifications(const st
 				notificationsVector.push_back(notification);
 			}
 		}
-		m_dataStore.unlockDataStore();
 		return notificationsVector;
 	}
 	else