Run user type initializers before the catch-all ObjectTypeInitializer

[ruudk]

The @hook directive added in #43 forwards $this->hooks into child constructors via ObjectTypeInitializer, which consults a ClassHookUsageRegistry owned by PlanExecutor. Projects that registered their own ObjectTypeInitializer via Config::withTypeInitializer() to customize a specific value object (Money, Url, …) broke the hook forwarding: the dedup-by-class-name in DelegatingTypeInitializer let the user instance — constructed without the registry — overwrite the built-in one, so every new Child($data) was emitted without hooks.

Splitting the two roles removes the footgun. ObjectTypeInitializer is now strictly the internal catch-all (registry injected via constructor, no extension surface). Userland registers plain TypeInitializer instances that match only their specific class; the delegation chain runs them ahead of the catch-all, so type-specific handlers win for their own types and everything else falls through to the built-in one with hooks intact.

Breaking change for any config that wrapped a handler in ObjectTypeInitializer — unwrap it and pass the inner TypeInitializer directly to withTypeInitializer().