Show Send when a running thread has draft content. Separate submission follow
from first-message anchoring so later sends do not reserve extra blank space.
Restore Android initial composer insets and iOS focus-aware dictation insets.

Keep opening and final assistant replies visible around completed folds,
anchoring Worked for at the first hidden item while preserving v2 relationship
cards and execution-attempt behavior.

Validation: 107 focused tests and the mobile typecheck pass. Formatting passes;
scoped lint and React Doctor report warnings but no errors. No simulator run.