Make the Preamble one click accessible

[erinepshovel-code]

Purpose

Makes the Preamble directly reachable in one click from the public homepage and from every generated page through the primary navigation.

Change

• adds stable /preamble/ route generated from the selected canonical Preamble unit
• places Preamble in the primary navigation
• makes Read the Preamble the first homepage action and adds a dedicated homepage card
• preserves canonical provenance, source lines, and unit digest on the page
• adds generated-artifact, browser-navigation, and accessibility regression checks

File plan

Path	Change	Purpose	Risk	Required evidence
src/preamble/index.njk	create	stable canon-derived Preamble route	missing or renamed canon unit	generated-site test
src/index.njk	modify	one-click homepage entrance	navigation clutter	browser test
src/_includes/layouts/base.njk	modify	one-click access from all pages	mobile navigation width	browser/accessibility gate
tests/*	modify	prevent regression	none	full PR workflow

Canon boundary

The page does not copy or replace canon. It selects the Preamble unit from generated canon data on every build and exposes its provenance and digest.

hmmm

The Preamble is now treated as an entrance, not something hidden behind the general Way index.