refactor: extract token validation into reusable method

- Add validateProviderToken() helper method to reduce code duplication
- Use request body only ($request->json()->all()) to avoid route parameter conflicts
- Add proper logging for token validation failures
- Add missing DB import to migration file
- Minor test formatting fix

🤖 Generated with Claude Code

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

database/migrations/2024_11_19_000001_add_uuid_to_cloud_provider_tokens.php

@@ -2,6 +2,7 @@
 
 use Illuminate\Database\Migrations\Migration;
 use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\DB;
 use Illuminate\Support\Facades\Schema;
 use Visus\Cuid2\Cuid2;