Tokenizer offers Create for a label that is already selected when the token id differs from the label

what happens

with a selected token like {id: 'u1', label: 'Alice'}, typing "Alice" again still offers Create "Alice", and committing it adds a duplicate token under a fresh id.

why

the hasCreate duplicate check compares the typed label against the set of selected ids, not labels. the search results can't catch it either because they are pre-filtered to remove selected items.

repro

1. select a token whose label differs from its id
2. type that label again
3. the create action is offered and duplicates the entry

expected

the create action is suppressed when the typed label matches an already-selected token's label (case-insensitive), same as it is today when label equals id.

env: main 5a7b819