Consolidate custom post type and meta registrations into Post_Types class

- Created new Post_Types class to manage all custom post type and meta registrations
- Moved post type registrations from Activitypub::register_post_types() to dedicated methods
- Consolidated post meta registration with each post type for better organization
- Removed duplicate post meta registrations from Blocks class
- Updated tests to use new Post_Types class methods
- Maintained user meta registrations in original Activitypub class location
- All 895 tests pass, ensuring backward compatibility

Author: obenland

activitypub.php

@@ -80,6 +80,7 @@ function plugin_init() {
 	\add_action( 'init', array( __NAMESPACE__ . '\Migration', 'init' ), 1 );
 	\add_action( 'init', array( __NAMESPACE__ . '\Move', 'init' ) );
 	\add_action( 'init', array( __NAMESPACE__ . '\Options', 'init' ) );
+	\add_action( 'init', array( __NAMESPACE__ . '\Post_Types', 'init' ) );
 	\add_action( 'init', array( __NAMESPACE__ . '\Scheduler', 'init' ) );
 	\add_action( 'init', array( __NAMESPACE__ . '\Search', 'init' ) );
 	\add_action( 'init', array( __NAMESPACE__ . '\Signature', 'init' ) );