feat: 회원가입 + 테넌트 생성 통합 API 추가 (/api/v1/register)

- 사용자 등록 + 테넌트 생성 + 시스템 관리자 권한 자동 부여
- 사업자번호 조건부 검증 (active 테넌트만 unique)
- 글로벌 메뉴 자동 복제 (parent_id 매핑 알고리즘)
- DB 트랜잭션으로 전체 프로세스 원자성 보장

추가:
- RegisterRequest: FormRequest 검증 (conditional unique)
- RegisterService: 9-step 통합 비즈니스 로직
- RegisterController: ApiResponse::handle() 패턴
- RegisterApi: 완전한 Swagger 문서

수정:
- MenusStep: 글로벌 메뉴 복제 로직 구현
- message.php: 'registered' 키 추가
- error.php: 4개 에러 메시지 추가
- routes/api.php: POST /api/v1/register 라우트

SAM API Rules 준수:
- Service-First, FormRequest, i18n, Swagger, DB Transaction

app/Services/RegisterService.php

@@ -0,0 +1,130 @@
+<?php
+
+namespace App\Services;
+
+use App\Models\Commons\Menu;
+use App\Models\Members\User;
+use App\Models\Tenants\Tenant;
+use App\Models\Tenants\TenantUserProfile;
+use App\Services\TenantBootstrap\RecipeRegistry;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Facades\Hash;
+use Spatie\Permission\Models\Permission;
+use Spatie\Permission\Models\Role;
+use Spatie\Permission\PermissionRegistrar;
+
+class RegisterService
+{
+    /**
+     * 회원가입 처리 (테넌트 생성 + 사용자 생성 + 시스템 관리자 역할 부여)
+     *
+     * @param  array  $params  [
+     *                         'user_id' => string,
+     *                         'name' => string,
+     *                         'email' => string,
+     *                         'phone' => string,
+     *                         'password' => string,
+     *                         'position' => string (optional),
+     *                         'company_name' => string,
+     *                         'business_num' => string (optional),
+     *                         'company_scale' => string (optional),
+     *                         'industry' => string (optional),
+     *                         ]
+     * @return array ['user' => array, 'tenant' => array]
+     */
+    public static function register(array $params): array
+    {
+        return DB::transaction(function () use ($params) {
+            // 1. Create Tenant with trial status and options
+            $tenant = Tenant::create([
+                'company_name' => $params['company_name'],
+                'business_num' => $params['business_num'] ?? null,
+                'tenant_st_code' => 'trial', // 트라이얼 상태
+                'options' => [
+                    'company_scale' => $params['company_scale'] ?? null,
+                    'industry' => $params['industry'] ?? null,
+                ],
+            ]);
+
+            // 2. Bootstrap tenant (STANDARD recipe: CapabilityProfiles, Categories, Menus, Settings)
+            // This will create all necessary menus via MenusStep
+            app(RecipeRegistry::class)->bootstrap($tenant->id, 'STANDARD');
+
+            // 3. Create User with hashed password and options
+            $user = User::create([
+                'user_id' => $params['user_id'],
+                'name' => $params['name'],
+                'email' => $params['email'],
+                'phone' => $params['phone'] ?? null,
+                'password' => Hash::make($params['password']),
+                'options' => [
+                    'position' => $params['position'] ?? null,
+                ],
+            ]);
+
+            // 4. Create TenantUserProfile (tenant-user mapping)
+            TenantUserProfile::create([
+                'user_id' => $user->id,
+                'tenant_id' => $tenant->id,
+                'is_default' => 1, // 기본 테넌트로 설정
+                'is_active' => 1, // 활성화
+            ]);
+
+            // 5. Set tenant context for permissions
+            // This is critical for Spatie permissions to work correctly
+            app()->bind('tenant_id', fn () => $tenant->id);
+            app(PermissionRegistrar::class)->setPermissionsTeamId($tenant->id);
+
+            // 6. Create 'system_manager' role
+            $role = Role::create([
+                'tenant_id' => $tenant->id,
+                'guard_name' => 'api',
+                'name' => 'system_manager',
+                'description' => '시스템 관리자',
+            ]);
+
+            // 7. Get all tenant menus (after bootstrap)
+            $menuIds = Menu::where('tenant_id', $tenant->id)->pluck('id');
+
+            // 8. Create permissions for each menu and assign to role
+            $permissions = [];
+            foreach ($menuIds as $menuId) {
+                $permName = "menu.{$menuId}";
+
+                // Use firstOrCreate to avoid duplicate permission errors
+                $perm = Permission::firstOrCreate([
+                    'tenant_id' => $tenant->id,
+                    'guard_name' => 'api',
+                    'name' => $permName,
+                ]);
+
+                $permissions[] = $perm;
+            }
+
+            // 9. Assign all menu permissions to system_manager role
+            $role->syncPermissions($permissions);
+
+            // 10. Assign system_manager role to user
+            $user->assignRole($role);
+
+            // 11. Return user and tenant data
+            return [
+                'user' => [
+                    'id' => $user->id,
+                    'user_id' => $user->user_id,
+                    'name' => $user->name,
+                    'email' => $user->email,
+                    'phone' => $user->phone,
+                    'options' => $user->options,
+                ],
+                'tenant' => [
+                    'id' => $tenant->id,
+                    'company_name' => $tenant->company_name,
+                    'business_num' => $tenant->business_num,
+                    'tenant_st_code' => $tenant->tenant_st_code,
+                    'options' => $tenant->options,
+                ],
+            ];
+        });
+    }
+}