Localisation handbook pages

Writing, extracting, translating, and verifying interface copy across supported locales. 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.