Move increment/decrement handlers from Cart LiveView into CartHook so
they work from any page's drawer. Enable show_quantity_controls on the
drawer's cart_item_row. Scope cart tests to #main-content to avoid
duplicate button matches.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
- Cart context with pure functions for add/remove/update/hydrate
- Price formatting via ex_money (replaces all float division)
- CartHook on_mount with attach_hook for shared event handlers
(open/close drawer, remove item, PubSub sync)
- Accessible cart drawer with focus trap, scroll lock, aria-live
- Cart page with increment/decrement quantity controls
- Preview mode cart drawer support in theme editor
- Cart persistence to session via JS hook + API endpoint
- 19 tests covering all Cart pure functions
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
