refactor: let attributes declare what they register

[ogorzalka]

First step of extracting the attributes into pollora/attributes (roadmap, short term). Nothing moves yet: Pollora\Attributes stops reaching Laravel and the framework's services, so the next PR can move it as is. No class name changes.

What changes

• Post type and taxonomy attributes (69) implement ConfiguresArguments::configureArguments(array): array, a pure function of their own values; the discoveries apply it. The method attributes (AdminCol, RegisterMetaBoxCb, MetaBoxCb, MetaBoxSanitizeCb, UpdateCountCallback) implement ConfiguresArgumentsWithMethod: the discovery builds the callback, the attribute says where it goes. Custom attributes implementing HandlesAttributes still go through handle().
• #[WpRestRoute\Method] keeps its data and HTTP verb validation; WpRestRouteRegistrar (WpRest module) registers the route, unchanged.
• handle() removed from Action, Filter, WpRestRoute, Method: HookDiscovery and WpRestDiscovery register hooks and routes themselves.
• Default names (post type/taxonomy slugs, meta keys, WP-CLI commands) come from an internal Naming helper; a parity test pins it to Str::snake() / Str::kebab(). Pollora\Support\Slug delegates to it.
• Architecture test tests/Unit/Attributes/ArchitectureTest.php: attributes may only use themselves and the enumerations that will travel with them (AjaxAccess, Behaviour, BindingFieldType, Control, Access, Every, Interval).
• Deprecated: PostTypeAttribute, TaxonomyAttribute (no built-in attribute extends them), removed in 15.0.
• PHPStan baseline: 3 entries fewer (the registrar is typed on the wrapper).

Bug fixed on the way

A public #[Action]/#[Filter] method in a #[PostType] or #[Taxonomy] class was registered twice: the discovery called Action::handle() with its configuration object as the instance. Reproduced on a project (#[Action('wp_footer')] on a post type): 500 call_user_func(): ... PostTypeConfiguration does not have a method "footerProbe". With this branch: 200, method run once.

Non-regression

• 1975 tests (1954 before: −13 tests of the removed handle(), rewritten as HookDiscoveryTest against the discovery; +34 new), PHPStan 0, type coverage 99.2 %.
• On pollora-test (develop + this diff): get_post_type_object() / get_taxonomy() dumped for the 10 post types and 11 taxonomies, identical with and without the change; REST routes starter/v1/status and /projects answer byte for byte the same.