The codex resume test was the only replay scenario without a
runtimePolicyOverride, so its checkpoint scope cwd fell back to
process.cwd() and baseline capture ran real git over the entire
checkout. Locally the capture short-circuits on checkpoint refs left
behind by earlier runs; on a fresh CI checkout it is a cold multi-second
capture that outlives the scenario wait budget, failing await_thread_idle
while the run is still mid-checkpoint. Point the fixture's turn/start
frames at the <workspace> placeholder and checkpoint a throwaway git
workspace like every other replay test.

Scenario waits are also wall-clock-bounded now: the iteration budget
counts event-loop turns, which burn at full speed while git/fixture IO
is in flight, so exhaustion additionally requires a 60s real-time
deadline to pass.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>