A reasoning model's turn showed its thinking below its answer while
streaming, then flipped to thinking-above-answer once the turn settled.
One message is rendered by two components with opposite ordering rules:
while streaming, an AI message with content and reasoning but no tool
calls yet is deliberately held out of the terminal bubble (#4304) and
rendered by MessageGroup's chain-of-thought panel, which pinned the
trailing reasoning disclosure to the bottom; the settled bubble paints
its <Reasoning> disclosure above the content.
Render the trailing reasoning disclosure before the assistant text that
follows it, and emit a message's reasoning step before its content step
in convertToSteps -- the step list was content-first, so ordering by
step position alone could not fix it. Assistant text emitted before that
reasoning keeps its earlier position.
This also covers two cases the report does not mention: tool-using turns
reversed the same way, and expanding "N more steps" showed a message's
answer above its own thinking.
