Detect N+1 queries: dispatch an event on lazy relation load #590

When a relation is accessed without with(), Active Record silently runs one query per model, and there is currently no way to observe it.

foreach (Customer::query()->all() as $customer) {
    $customer->getOrders();
}

AbstractActiveRecord::retrieveRelation() is the single entry point for lazy loading, so a BeforeLazyRelationLoad event dispatched from EventsTrait would make this detectable by a listener.

EventDispatcherProvider::set(CustomerEventsModel::class, new Dispatcher(new Provider(
    (new ListenerCollection())->add(
        new LazyLoadGuard(LazyLoadGuardMode::Strict),
        BeforeLazyRelationLoad::class,
    ),
)));

// LogicException: Relation "App\Customer::orders" is lazy loaded.

Modes: Off (default — nothing is logged or thrown; the only cost is one event dispatch per lazy load), Log (PSR-3 warning carrying relation name, per-request count and trace), Strict (throws LogicException). Scoping per model class via only/except, on top of the existing use EventsTrait opt-in. Default behaviour of existing code is unchanged.