feat:sales_consultations에 gcs_uri 컬럼 추가

- 음성 녹음 파일의 Google Cloud Storage URI 저장용

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

database/migrations/2026_01_29_093000_add_gcs_uri_to_sales_consultations.php

@@ -0,0 +1,29 @@
+<?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('sales_consultations', function (Blueprint $table) {
+            $table->string('gcs_uri', 500)->nullable()->after('duration')
+                ->comment('Google Cloud Storage URI (본사 연구용 백업)');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('sales_consultations', function (Blueprint $table) {
+            $table->dropColumn('gcs_uri');
+        });
+    }
+};