feat: [approval] 결재관리 Phase 1 마이그레이션

- approvals 테이블: line_id, body, is_urgent, department_id 컬럼 추가
- approval_steps 테이블: approver_name, approver_department, approver_position 스냅샷 컬럼 추가

database/migrations/2026_02_27_100001_add_columns_to_approvals_table.php

@@ -0,0 +1,37 @@
+<?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::table('approvals', function (Blueprint $table) {
+            $table->foreignId('line_id')->nullable()->after('form_id')
+                ->constrained('approval_lines')->nullOnDelete()
+                ->comment('결재선 템플릿 ID');
+            $table->longText('body')->nullable()->after('content')
+                ->comment('본문 내용');
+            $table->boolean('is_urgent')->default(false)->after('status')
+                ->comment('긴급 여부');
+            $table->unsignedBigInteger('department_id')->nullable()->after('drafter_id')
+                ->comment('기안 부서 ID');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('approvals', function (Blueprint $table) {
+            $table->dropForeign(['line_id']);
+            $table->dropColumn(['line_id', 'body', 'is_urgent', 'department_id']);
+        });
+    }
+};

database/migrations/2026_02_27_100002_add_columns_to_approval_steps_table.php

@@ -0,0 +1,33 @@
+<?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::table('approval_steps', function (Blueprint $table) {
+            $table->string('approver_name', 50)->nullable()->after('approver_id')
+                ->comment('결재자명 스냅샷');
+            $table->string('approver_department', 100)->nullable()->after('approver_name')
+                ->comment('결재자 부서 스냅샷');
+            $table->string('approver_position', 50)->nullable()->after('approver_department')
+                ->comment('결재자 직급 스냅샷');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('approval_steps', function (Blueprint $table) {
+            $table->dropColumn(['approver_name', 'approver_department', 'approver_position']);
+        });
+    }
+};