Added employee persistence, serialization, and file loading support

<SRS>SRS02 : Employee Management </SRS>

<Changes>
 - Implemented serialization and deserialization for Employee and GeneralEmployee models
 - Added FileManager integration to load employees from CSV files
 - Introduced ApplicationConfig entries for employee file paths
 - Updated Employee ID handling (getEmployeeId → getId) across project
 - Modified FileIO to auto-create file if not found instead of throwing exception
 - Added constructors for all employee types to support deserialization
 - Implemented loadEmployees in service and loadStates in controller
 - Ensured default admin creation if none exists during load
 - Added StringHelper utility for extracting numeric IDs
 - Extended Enums with string conversion and parsing utilities
 - Added initial CSV files for Employee and GeneralEmployee data
 - Improved login error message formatting and minor cleanup
 - Setup gitignore to not track csv files
</Changes>

Trenser.Zenvy/Trenser.Zenvy/models/ITExecutive.h

@@ -10,7 +10,24 @@ public:
         const std::string& phone,
         const std::string& email,
         std::shared_ptr<Payroll> payroll
-    ) :Employee(name, phone, email, Enums::EmployeeType::GENERAL, payroll) {};
+    ) :Employee(name, phone, email, Enums::EmployeeType::IT, payroll) {};
+    ITExecutive(const std::string& id,
+        const std::string& name,
+        const std::string& phone,
+        const std::string& password,
+        const std::string& email,
+        const std::string& teamId,
+        Enums::TeamStatus teamStatus,
+        Enums::AccountStatus accountStatus)
+        : Employee(id,
+            name,
+            phone,
+            password,
+            email,
+            teamId,
+            teamStatus,
+            Enums::EmployeeType::IT,
+            accountStatus) {}
     ~ITExecutive() = default;
 };