Patch Changes
- 0aada94: Allow the new chat control to fill the available history rail space.
- 0aada94: Show relative cost per model in the composer's model picker. Each row now
carries a quiet$/$$/$$$suffix so a user can tell an entry model from a
flagship one before selecting it, rather than discovering the difference in
their bill. The tier reuses the token list the picker already sorts by
(MODEL_COST_ORDER) and reflects each provider's own entry/mid/flagship ladder
— it is not a cross-provider price claim. Models outside that list render with
no label at all; a guessed tier would read as fact.