- Add config/cors.php with supports_credentials=true and allowed_origins for app.dev.lernschiff.com
- Add routes/api_v1.php with auth:web-guarded /api/v1/me and /api/v1/users endpoints
- Add CrossSubdomainSessionTest covering OPTIONS 204 preflight and authenticated GET /api/v1/me
- Wire api_v1.php into routes/web.php
- Note: sanctum not installed; auth:web guard used instead of auth:sanctum,web