[ISSUE-032] Shopping List Mobile Interface

## Phase 5: AI Infrastructure & Meal Planning (Weeks 7-9)

### Description
Create shopping list screen from meal plan
Group ingredients by category
Add check-off functionality
Show estimated costs
Implement list sharing functionality

### Dependencies
- #030

### Can Work in Parallel With
- #031

Start by reviewing dependency #030 and the repository's existing mobile interface patterns. Treat the issue requirements as the completion checklist: create the shopping list from the meal plan, group ingredients, support checking items off, show estimated costs, and enable sharing.

Written by the indexing model from the issue text.