fork of prime agent with changes i want but are not upstreamable probqbly (and some fixes)

[RSI] feat(coding-agent): hold autonomous continuations while subagents run (#2284) master

* feat(coding-agent): hold autonomous continuations while subagents run * fix(coding-agent): address review findings on the subagent continuation gate * fix(coding-agent): keep the subagent keep-alive valve under budget limits * fix(coding-agent): deliver owed continuations past sibling notices; format tiny keep-alive windows * fix(coding-agent): decide owed continuations before spending their budget