* test(claude): reproduce fork child deadlock when init never arrives
* fix(claude): accept first fork child prompt on SessionStart:fork hook
A forked child starts query() before any prompt exists, and the SDK
emits 'init' only after the first prompt is sent. Waiting for init
deadlocked fork children until forever. Materialization is already
signaled by the SessionStart:fork hook, so accept the child prompt on
that signal instead.
* chore: restore bun.lock
