4bc0d58b

By: Michael Lynch <git@mtlynch.io>

Block empty-section adds until users confirm

Warn on the root grocery form before sending an HTMX add request when the section field is blank.

This moves the warning into the htmx:confirm phase so the request is blocked before it is posted, adds a reusable dialogManager API for custom confirm dialogs, and configures the empty-section warning so Edit is the default-focused action on the right while Add without section remains an explicit warning action.

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