Validates the chrome entities (header, footer, notice) declared inside
the layout section of MishkaGervaz form DSL.
Three checks, in order:
- Notice names are unique within a form.
- Notice positions are valid atoms or
{:before_group, name}/{:after_group, name}tuples that reference an existing group. - Notice
only_stepsreferences existing step names.
Position-shape validation is delegated to
MishkaGervaz.Form.Entities.Notice.validate_position/1.
See MishkaGervaz.Form.Dsl.Layout,
MishkaGervaz.Form.Entities.Notice,
MishkaGervaz.Form.Verifiers.Helpers, and sibling verifiers.