test: mounted_fan_out_recovers_then_synthesizes_and_hands_off flakes under load #4056

//crates/tracedecay:daemon_suite advanced_workflow_journey_test::mounted_fan_out_recovers_then_synthesizes_and_hands_off failed in batch gates on 2026-10-13 (three times) and again on 2026-10-15 after #4052 moved work and workflow dispatch onto the blocking pool. The 2026-10-15 failure read workflow transport unavailable. Each time it passed 3/3 when rerun alone, so it fails only under host load.

Find what the test waits on with a wall-clock budget, or which transport readiness it assumes, and make it wait on the daemon's own answer. If the daemon really reports the transport unavailable while it is mounted, fix that in production.