feat : Main Request 모델 추가, Enum 클래스 추가

- Main Request가 모든 공정을 관리하는 형태

app/Repositories/MainRequestRepository.php

@@ -0,0 +1,44 @@
+<?php
+namespace App\Repositories;
+
+use App\Models\MainRequest;
+use App\Models\MainRequestEstimate;
+use App\Models\MainRequestOrder;
+use App\Models\MainRequestFlow;
+
+class MainRequestRepository
+{
+    // 메인 업무 단건 조회
+    public function find($id)
+    {
+        return MainRequest::with(['flows', 'estimates', 'orders'])->find($id);
+    }
+
+    // 견적 생성
+    public function createEstimate($mainRequestId, array $data)
+    {
+        $data['main_request_id'] = $mainRequestId;
+        return MainRequestEstimate::create($data);
+    }
+
+    // 주문 생성
+    public function createOrder($mainRequestId, array $data)
+    {
+        $data['main_request_id'] = $mainRequestId;
+        return MainRequestOrder::create($data);
+    }
+
+    // 이력(Flow) 기록
+    public function addFlow($mainRequestId, $flowableType, $flowableId, $status, $action, $actorId, $content = null)
+    {
+        return MainRequestFlow::create([
+            'main_request_id' => $mainRequestId,
+            'flowable_type'   => $flowableType,
+            'flowable_id'     => $flowableId,
+            'status_code'     => $status,
+            'action'          => $action,
+            'actor_id'        => $actorId,
+            'content'         => $content,
+        ]);
+    }
+}