Turn N+1 queries into errors in development with preventLazyLoading()

Called in a service provider, this throws a `LazyLoadingViolationException` whenever a relation is accessed without being eager-loaded. N+1 problems are invisible in code review and only show up as latency under load; this surfaces them the moment you hit the endpoint locally. Gate it to non-production so you never break a live request — the goal is to force `with()`/`load()` during development, not in front of users.