Accessibility handbook pages

Building and checking interfaces that work across input, vision, motion, and layout needs. 3 pages.

1. 01Packbase webWhere Packbase browser behaviour lives and how routes, components, SDK state, stories, localisation, and the Worker fit together.
2. 02Frontend changesA repeatable Packbase web workflow for routes, components, SDK state, accessibility, localisation, and stories.
3. 03Testing and documentationHow to choose proportionate checks, report evidence honestly, and keep repository and handbook guidance aligned with reality.