feat : 테이블 및 DB 마이그레이션 파일 추가

products
  - common_codes
  - parts
  - products
  - files
  - price_histories
  - boms
  - bom_items

  boards
  - boards
  - board_settings
  - posts
  - board_comments
  - board_files
  - post_custom_field_values

  permissions
  - menus
  - roles
  - user_menu_permissions
  - role_menu_permissions

  tenants
  - tenants
  - plans
  - subscriptions
  - payments

app/Models/Plan.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\SoftDeletes;
+
+class Plan extends Model
+{
+    use SoftDeletes;
+
+    protected $fillable = [
+        'name', 'code', 'description', 'price', 'billing_cycle', 'features', 'is_active',
+    ];
+
+    protected $casts = [
+        'features' => 'array',
+        'is_active' => 'boolean',
+        'price' => 'float',
+    ];
+
+    public function subscriptions() {
+        return $this->hasMany(Subscription::class);
+    }
+}