feat: [hr] 사업소득자 임금대장 입력 기능 구현

- BusinessIncomePayment 모델 (소득세3%/지방소득세0.3% 자동계산)
- BusinessIncomePaymentService (일괄저장/통계/CSV내보내기)
- 웹/API 컨트롤러 (ALLOWED_PAYROLL_USERS 접근 제한)
- 스프레드시트 UI (인라인 편집, 실시간 세금 계산)
- HTMX 연월 변경 갱신, CSV 내보내기

app/Http/Controllers/HR/BusinessIncomePaymentController.php

@@ -0,0 +1,48 @@
+<?php
+
+namespace App\Http\Controllers\HR;
+
+use App\Http\Controllers\Controller;
+use App\Services\HR\BusinessIncomePaymentService;
+use Illuminate\Contracts\View\View;
+use Illuminate\Http\Request;
+use Illuminate\Http\Response;
+
+class BusinessIncomePaymentController extends Controller
+{
+    private const ALLOWED_PAYROLL_USERS = ['이경호', '전진선', '김보곤'];
+
+    public function __construct(
+        private BusinessIncomePaymentService $service
+    ) {}
+
+    /**
+     * 사업소득자 임금대장 페이지
+     */
+    public function index(Request $request): View|Response
+    {
+        if ($request->header('HX-Request')) {
+            return response('', 200)->header('HX-Redirect', route('hr.business-income-payments.index'));
+        }
+
+        if (! in_array(auth()->user()->name, self::ALLOWED_PAYROLL_USERS)) {
+            return view('hr.payrolls.restricted');
+        }
+
+        $year = $request->integer('year') ?: now()->year;
+        $month = $request->integer('month') ?: now()->month;
+
+        $earners = $this->service->getActiveEarners();
+        $payments = $this->service->getPayments($year, $month);
+        $paymentsByUser = $payments->keyBy('user_id');
+        $stats = $this->service->getMonthlyStats($year, $month);
+
+        return view('hr.business-income-payments.index', [
+            'earners' => $earners,
+            'paymentsByUser' => $paymentsByUser,
+            'stats' => $stats,
+            'year' => $year,
+            'month' => $month,
+        ]);
+    }
+}