Store a _groceryState JSON field on each recipe to track which
ingredients have been added, completed, or removed. Uses per-item
last-writer-wins conflict resolution with ISO 8601 timestamps.
Debounced push (2s) avoids excessive API calls; pull reconciles
on recipe open and app launch. Includes a settings toggle to
enable/disable sync.
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
