Shared code between frontend and backend.

shared/
├── types.ts          # TypeScript interfaces and types
└── utils.ts          # Shared utility functions

• Code here must work in both browser and Deno environments
• Do NOT use the Deno keyword directly
• Use https://esm.sh for imports to ensure compatibility
• Keep dependencies minimal

• Recipe - Recipe metadata
• Ingredient - Recipe ingredient with quantity/unit
• Instruction - Recipe step
• RecipeWithDetails - Full recipe with ingredients and instructions

• IngestRequest - Recipe URL submission
• ShoppingListRequest - Shopping list generation request
• ShoppingListItem - Aggregated shopping list entry