docs: merge Adding-A-Page into Page-Layout, trim Move the four add-a-page steps into Eagle-Public-Page-Layout and delete Eagle-Public-Adding-A-Page. Tighten Extended-Project-Pages and Angular-Patterns: drop sentences other pages already hold and code samples that repeat a nearby one.
docs: add extended pages and Act registry - Extended-Project-Pages: content model, blocks, tab rules, validation, recipe for giving a project an extended page. - Project-Data-Models: legislation registry, locked Acts, steps for adding an Act. - Configuration-Management: EXTENDED_PROJECT_PAGES key and how to turn a page off.
docs: drop text width caps from eagle-public layout
docs(public): split new-page steps from layout The layout page mixed reference with a how-to, which the wiki rules do not allow. The steps move to their own page. The page-measure row named the wrong file for the compliance tab.
docs(public): add page layout guide Covers the shared page container, the blue band and breadcrumb components, default-hidden grid columns, and the parked pixel comparison in the visual parity suite. Matches eagle-public v3.0.0-beta.39.