feat:문서양식 결재라인 user_id 및 연결 필드 마이그레이션 추가

- document_template_approval_lines에 user_id 컬럼 추가
- document_templates에 linked_item_ids(JSON), linked_process_id 컬럼 추가

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

database/migrations/2026_02_03_110000_add_user_id_and_linked_fields_to_document_templates.php

@@ -0,0 +1,36 @@
+<?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
+    {
+        // 결재라인에 user_id 추가
+        Schema::table('document_template_approval_lines', function (Blueprint $table) {
+            $table->unsignedBigInteger('user_id')->nullable()->after('role')
+                ->comment('담당자 ID (작성 단계는 null)');
+        });
+
+        // 문서양식에 연결 필드 추가
+        Schema::table('document_templates', function (Blueprint $table) {
+            $table->json('linked_item_ids')->nullable()->after('is_active')
+                ->comment('수입검사 시 연결된 품목 ID 배열');
+            $table->unsignedBigInteger('linked_process_id')->nullable()->after('linked_item_ids')
+                ->comment('품질검사 시 연결된 공정 ID');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('document_template_approval_lines', function (Blueprint $table) {
+            $table->dropColumn('user_id');
+        });
+
+        Schema::table('document_templates', function (Blueprint $table) {
+            $table->dropColumn(['linked_item_ids', 'linked_process_id']);
+        });
+    }
+};