Added CSV header support and persistence for employees

<SRS> SRS02 : Employee Management </SRS>

<Changes>
 - Added header handling in FileManager load by skipping first line during deserialization
 - Added support for writing headers using T::getHeaders() in FileManager save
 - Implemented getHeaders() for Employee and GeneralEmployee models
 - Added saveEmployees functionality in EmployeeManagementService
 - Added persistStates method in ZenvyController
 - Added deserialization failure check with exception handling
 - Minor formatting cleanup in FileIO
</Changes>

<Review>
Smitha Mohan
</Review>

Trenser.FileManager/Trenser.FileManager/FileIO.cpp

@@ -22,7 +22,6 @@ void FileIO::writeAllLines(const std::string& path,
     std::ofstream file(path, std::ios::trunc);
     if (!file.is_open())
         throw std::runtime_error("Failed to open file " + path);
-
     for (const auto& line : lines)
         file << line << '\n';
-}
+}

Trenser.FileManager/Trenser.FileManager/FileManager.h

@@ -1,4 +1,5 @@
 #pragma once
+#include <stdexcept>
 #include "FileIO.h"
 
 template <typename T> using objects = std::map<std::string, std::shared_ptr<T>>;
@@ -20,9 +21,19 @@ objects<T> FileManager<T>::load()
 {
 	objects<T> records;
 	auto lines = FileIO::readAllLines(m_filePath);
+	bool isHeader = true;
 	for (const auto& record : lines)
 	{
+		if (isHeader)
+		{
+			isHeader = false;
+			continue;
+		}
 		auto object = T::deserialize(record);
+		if (!object)
+		{
+			throw std::runtime_error("Failed to deserialize record");
+		}
 		records[object->getId()] = object;
 	}
 	return records;
@@ -32,7 +43,7 @@ template <typename T>
 void FileManager<T>::save(const objects<T>& records)
 {
 	std::vector<std::string> lines;
-
+	lines.push_back(T::getHeaders());
 	for (const auto& recordPair : records)
 	{
 		lines.push_back(recordPair.second->serialize());