Migrate the SCF post editing pages to leverage Core Components

SCF currently uses custom PHP form and field helper functions to build interfaces for creating and editing Field Groups, Post Types, Taxonomies, and Options Pages post types. This project aims to rebuild the SCF's post types editing logic (post.php) by leveraging native WordPress components such as DataForms and other core UI elements. The goal is to modernize and simplify these editing pages, improving maintainability and user experience by aligning with WordPress core design patterns.

Additional Context

• It should be started after #142 begins.
• It should be implemented with reusability in mind, e.g., to integrate them in the block editor for quick editing.
• We should start with Taxonomies, as it is closely related to #155 and simpler than other types.
• It should be introduced as an opt-in Beta feature.

Tasks

• Migrate the Taxonomies editing page to native components
• Migrate the Field Groups editing page to native components
• Migrate the Post Types editing page to native components
• Migrate the Options Pages to native components
• Explore embedding these in the Editor, for example to Edit Taxonomies as in #155

Start with post.php after #142 begins, and review the related scope in #155. Begin with the Taxonomies editing page and study how WordPress DataForms and other native components can support reusable editing interfaces. Done means the editing pages are migrated with an opt-in Beta feature, covering the listed post types and documenting the Editor embedding exploration.