chore(psr4): phase 3 (Core) — namespace Core/Events

Move Core/Events into XcVm\Core\Events and its sub-trees: \Contract
(StoppableEventInterface), \Auth, \Module, \Settings, \Stream (the event
classes), plus root EventDispatcher, ListenerProvider, ListensTo, AbstractEvent.

- Namespace 14 files across 6 namespaces; cross-namespace refs imported via use
  (AbstractEvent/EventDispatcher → Contract\StoppableEventInterface; Stream events
  → root AbstractEvent). Built-in \Attribute (ListensTo) and ioncube \XC_VM
  (PackageInstalledEvent) qualified.
- Rewrite 'use ListensTo;' → FQCN; add use to referrers across src/ and tests/;
  fix leading-backslash refs (\EventDispatcher, \ListensTo, \PackageInstalledEvent
  from the Module commit) to their FQCNs.
- Tests: add real top-level use imports to ModuleLoaderBootTest (EventDispatcher)
  and ListensToAttributeTest (ListensTo) — the use-inserter skipped/mis-placed them
  due to a namespace() method and a heredoc fixture already containing the FQCN.
- phpstan-baseline.neon regenerated (292→292).

Completes Core/Container + Core/Events. Verified: php -l clean; PHPStan no errors;
PHPUnit 295/295; EventDispatcher resolves and AbstractEvent implements
XcVm\Core\Events\Contract\StoppableEventInterface.

tests/Unit/ModuleLoaderBootTest.php

@@ -5,6 +5,7 @@ use XcVm\Core\Module\ModuleLoader;
 use XcVm\Core\Module\NavbarRegistry;
 use XcVm\Core\Module\ModuleInterface;
 use XcVm\Core\Container\ServiceContainer;
+use XcVm\Core\Events\EventDispatcher;
 use PHPUnit\Framework\TestCase;
 
 // Shared tracker — loaded by PHPUnit before any module PHP file is require_once'd by ModuleLoader.