cc5d6bab

By: Michael Lynch <git@mtlynch.io>

Keep item-section JSON details in handlers

Use ItemName for ItemSection.Name so remembered item-section mappings use the same validated item-name type as grocery items. Move JSON field names into a private handler response type so the shared types package remains transport-agnostic.

Testing:
- GOBIN= ./dev-scripts/run-go-tests
- nix flake check
- ./dev-scripts/git-hooks/pre-commit