Migrate interface test blocks to page.test.ts and component.test.ts

Extract test describe blocks from the deleted interface.test.ts and append
them to their correct test files based on the schemas they test:

- page.test.ts: PageTypeSchema, RecordReviewConfigSchema, PageSchema with
  page types, ElementDataSourceSchema, PageComponent dataSource integration,
  BlankPageLayoutSchema, PageVariableSchema record_id type, Page end-to-end
- component.test.ts: Content Elements, ElementTextPropsSchema,
  ElementNumberPropsSchema, ElementImagePropsSchema, ComponentPropsMap
  content elements, Interactive Elements (button, filter, form,
  record_picker), ComponentPropsMap interactive elements

All InterfaceSchema/defineInterface references removed. The Interface
end-to-end test was transformed into a Page end-to-end test that validates
complex page definitions with regions, components, record review config,
and data sources.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Copilot