feat(api): 사업자등록증 OCR용 biz_cert 테이블 마이그레이션 추가

- biz_cert 테이블 생성 (사업자등록번호, 상호, 대표자, 개업일, 주소, 업태, 종목, 발급일)
- raw_text, ocr_method 필드 추가 (OCR 원본 텍스트 및 처리 방식 저장)
- biz_no, company_name 인덱스 추가

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

database/migrations/2025_12_16_012109_create_biz_cert_table.php

@@ -0,0 +1,40 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::create('biz_cert', function (Blueprint $table) {
+            $table->id();
+            $table->string('biz_no', 12)->comment('사업자등록번호');
+            $table->string('company_name', 100)->comment('상호');
+            $table->string('representative', 50)->nullable()->comment('대표자');
+            $table->date('open_date')->nullable()->comment('개업일');
+            $table->string('address', 255)->nullable()->comment('주소');
+            $table->string('biz_type', 100)->nullable()->comment('업태');
+            $table->string('biz_item', 255)->nullable()->comment('종목');
+            $table->date('issue_date')->nullable()->comment('발급일');
+            $table->text('raw_text')->nullable()->comment('OCR 원본 텍스트');
+            $table->string('ocr_method', 20)->default('claude')->comment('OCR 방식 (tesseract/claude)');
+            $table->timestamps();
+
+            $table->index('biz_no');
+            $table->index('company_name');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::dropIfExists('biz_cert');
+    }
+};