feat: [hr] 사업소득자 임금대장 display_name/business_reg_number 컬럼 추가

- user_id nullable 변경 (직접 입력 대상자 지원)
- display_name, business_reg_number 컬럼 추가
- 기존 데이터 earner 프로필에서 자동 채움

database/migrations/2026_03_03_100000_add_display_name_to_business_income_payments.php

@@ -0,0 +1,47 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::table('business_income_payments', function (Blueprint $table) {
+            $table->unsignedBigInteger('user_id')->nullable()->change();
+            $table->string('display_name', 100)->nullable()->after('user_id')->comment('상호/성명 (표시용)');
+            $table->string('business_reg_number', 20)->nullable()->after('display_name')->comment('사업자등록번호');
+        });
+
+        // 기존 데이터에 display_name/business_reg_number 채우기
+        DB::statement("
+            UPDATE business_income_payments bip
+            JOIN tenant_user_profiles tup ON tup.user_id = bip.user_id
+                AND tup.tenant_id = bip.tenant_id AND tup.worker_type = 'business_income'
+            SET bip.display_name = COALESCE(
+                JSON_UNQUOTE(JSON_EXTRACT(tup.json_extra, '$.business_name')),
+                (SELECT name FROM users WHERE id = bip.user_id)
+            ),
+            bip.business_reg_number = JSON_UNQUOTE(JSON_EXTRACT(tup.json_extra, '$.business_registration_number'))
+            WHERE bip.display_name IS NULL
+        ");
+
+        // earner 프로필 없는 경우 users 테이블에서 이름만이라도 채우기
+        DB::statement("
+            UPDATE business_income_payments bip
+            JOIN users u ON u.id = bip.user_id
+            SET bip.display_name = u.name
+            WHERE bip.display_name IS NULL AND bip.user_id IS NOT NULL
+        ");
+    }
+
+    public function down(): void
+    {
+        Schema::table('business_income_payments', function (Blueprint $table) {
+            $table->dropColumn(['display_name', 'business_reg_number']);
+            $table->unsignedBigInteger('user_id')->nullable(false)->change();
+        });
+    }
+};