fix(agents): honor subagent model routing (#112393)
<pre style='white-space:pre-wrap;width:81ex'>fix(agents): honor subagent model routing (#112393) Forward explicit sessions_spawn model choices through direct and queued child launches, and persist the exact authorization so restart replay cannot silently fall back to the default route. Fixes #91171. Co-authored-by: mikasa0818 <0668001030@xydigit.com></pre>


