feat: 출퇴근 설정에 자동 출퇴근 사용 여부 필드 추가

- attendance_settings 테이블에 use_auto 컬럼 추가
- AttendanceSetting 모델에 use_auto 필드 추가 (fillable, casts, attributes)
- UpdateAttendanceSettingRequest에 use_auto 유효성 검사 추가

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

database/migrations/2026_01_27_144110_add_use_auto_to_attendance_settings.php

@@ -0,0 +1,28 @@
+<?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('attendance_settings', function (Blueprint $table) {
+            $table->boolean('use_auto')->default(false)->after('use_gps')->comment('자동 출퇴근 사용 여부');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('attendance_settings', function (Blueprint $table) {
+            $table->dropColumn('use_auto');
+        });
+    }
+};