Keep chat composer actions visible during transitions

[hamzamerzic]

Summary

• keep Send, Steer, and Stop on one stable primary action control
• remove the opacity-zero reveal that caused a blank frame between actions
• cover both the shared control identity and the no-fade visual contract

Testing

• npm test
• npm run build
• rendered check confirmed Send → Stop and Steer → Stop remain fully opaque with no action animation

[hamzamerzic]

Superseded by the reviewed visual integration in #295, which preserves this change and its authorship. The integration is now moving through the merge queue.