feature: header dsl

[Paul-Bob]

Description

WIP

This PR introduces the following changes:

• header DSL

  • Can now be used anywhere within the def fields method.
  • Renders the resource’s title, description, discreet information, and controls.
  • If a header is not explicitly defined, one is automatically generated and placed at the top of the page.

• main_panel DSL is obsolete

  • main_panel is now obsolete and should be replaced with panel.
  • Previously, fields defined within main_panel were automatically rendered on the index page. Since the concept of a “main panel” has been removed, a temporary option—show_fields_on_index—has been introduced to preserve and extend this behavior.
  • This option provides more flexibility and customization for index views. Since users can now choose which panels’ fields are visible on the index, it becomes possible to have (for example) three panels on the show view while displaying their fields on the index as well—without needing to duplicate any definitions.

TODO

• [ ] Refactor or rename the temporary show_fields_on_index option.
• [ ] Document new DSL and breaking changes