feat: [payroll] 엑셀 내보내기 및 전표 생성 API 추가

- GET /payrolls/export: 급여 현황 엑셀 다운로드 (필터 지원)
- POST /payrolls/journal-entries: 연월 기준 급여 전표 일괄 생성
- JournalEntry SOURCE_PAYROLL 상수 추가
- StorePayrollJournalRequest 유효성 검증 추가

app/Http/Controllers/Api/V1/PayrollController.php

@@ -8,16 +8,20 @@
 use App\Http\Requests\V1\Payroll\CalculatePayrollRequest;
 use App\Http\Requests\V1\Payroll\CopyFromPreviousPayrollRequest;
 use App\Http\Requests\V1\Payroll\PayPayrollRequest;
+use App\Http\Requests\V1\Payroll\StorePayrollJournalRequest;
 use App\Http\Requests\V1\Payroll\StorePayrollRequest;
 use App\Http\Requests\V1\Payroll\UpdatePayrollRequest;
 use App\Http\Requests\V1\Payroll\UpdatePayrollSettingRequest;
+use App\Services\ExportService;
 use App\Services\PayrollService;
 use Illuminate\Http\Request;
+use Symfony\Component\HttpFoundation\BinaryFileResponse;
 
 class PayrollController extends Controller
 {
     public function __construct(
-        private readonly PayrollService $service
+        private readonly PayrollService $service,
+        private readonly ExportService $exportService
     ) {}
 
     /**
@@ -218,6 +222,47 @@ public function payslip(int $id)
         return ApiResponse::success($payslip, __('message.fetched'));
     }
 
+    /**
+     * 급여 엑셀 내보내기
+     */
+    public function export(Request $request): BinaryFileResponse
+    {
+        $params = $request->only([
+            'year',
+            'month',
+            'status',
+            'user_id',
+            'department_id',
+            'search',
+            'sort_by',
+            'sort_dir',
+        ]);
+
+        $exportData = $this->service->getExportData($params);
+        $filename = '급여현황_'.date('Ymd_His');
+
+        return $this->exportService->download(
+            $exportData['data'],
+            $exportData['headings'],
+            $filename,
+            '급여현황'
+        );
+    }
+
+    /**
+     * 급여 전표 생성
+     */
+    public function journalEntries(StorePayrollJournalRequest $request)
+    {
+        $year = (int) $request->input('year');
+        $month = (int) $request->input('month');
+        $entryDate = $request->input('entry_date');
+
+        $entry = $this->service->createJournalEntries($year, $month, $entryDate);
+
+        return ApiResponse::success($entry, __('message.payroll.journal_created'));
+    }
+
     /**
      * 급여 설정 조회
      */