feat: [equipment] files 테이블에 GCS 컬럼 추가

- gcs_object_name, gcs_uri 컬럼 추가
- 설비 사진 멀티 업로드 기능 지원

database/migrations/2026_02_25_110000_add_gcs_columns_to_files_table.php

@@ -0,0 +1,23 @@
+<?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
+    {
+        Schema::table('files', function (Blueprint $table) {
+            $table->string('gcs_object_name', 500)->nullable()->after('file_type')->comment('GCS 객체 경로');
+            $table->string('gcs_uri', 600)->nullable()->after('gcs_object_name')->comment('gs://bucket/object URI');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('files', function (Blueprint $table) {
+            $table->dropColumn(['gcs_object_name', 'gcs_uri']);
+        });
+    }
+};