feat: [hr] 사업소득자 임금대장 테이블 마이그레이션 추가

- business_income_payments 테이블 생성
- 소득세(3%)/지방소득세(0.3%) 고정세율 구조
- (tenant_id, user_id, pay_year, pay_month) 유니크 제약

database/migrations/2026_02_27_300000_create_business_income_payments_table.php

@@ -0,0 +1,44 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::create('business_income_payments', function (Blueprint $table) {
+            $table->id();
+            $table->foreignId('tenant_id')->constrained('tenants')->comment('테넌트');
+            $table->foreignId('user_id')->constrained('users')->comment('사업소득자 사용자');
+            $table->unsignedSmallInteger('pay_year')->comment('급여 연도');
+            $table->unsignedTinyInteger('pay_month')->comment('급여 월 (1-12)');
+            $table->string('service_content', 200)->nullable()->comment('용역내용');
+            $table->decimal('gross_amount', 15, 0)->default(0)->comment('지급총액');
+            $table->decimal('income_tax', 15, 0)->default(0)->comment('소득세 (3%)');
+            $table->decimal('local_income_tax', 15, 0)->default(0)->comment('지방소득세 (0.3%)');
+            $table->decimal('total_deductions', 15, 0)->default(0)->comment('공제합계');
+            $table->decimal('net_amount', 15, 0)->default(0)->comment('실지급액');
+            $table->date('payment_date')->nullable()->comment('지급일자');
+            $table->text('note')->nullable()->comment('비고');
+            $table->string('status', 20)->default('draft')->comment('상태: draft/confirmed/paid');
+            $table->timestamp('confirmed_at')->nullable()->comment('확정일시');
+            $table->foreignId('confirmed_by')->nullable()->constrained('users')->comment('확정자');
+            $table->timestamp('paid_at')->nullable()->comment('지급일시');
+            $table->foreignId('created_by')->nullable()->constrained('users')->comment('생성자');
+            $table->foreignId('updated_by')->nullable()->constrained('users')->comment('수정자');
+            $table->foreignId('deleted_by')->nullable()->constrained('users')->comment('삭제자');
+            $table->timestamps();
+            $table->softDeletes();
+
+            $table->unique(['tenant_id', 'user_id', 'pay_year', 'pay_month'], 'bip_tenant_user_period_unique');
+            $table->index(['tenant_id', 'pay_year', 'pay_month'], 'bip_tenant_period_idx');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::dropIfExists('business_income_payments');
+    }
+};