test(omo-senpi): pin the remediation hints for model-admission exhaustion

A model-admission exhaustion (`MemoryModelExhaustedError`) is finalized with reason
`spawn_failed`, the same reason a genuine executable-resolution failure carries, so the
remediation hint told a user whose models were all rate limited to set `SENPI_BIN` - for a
path where no child was ever spawned and no executable was ever resolved.

Pin the four detail shapes `formatMemoryModelExhaustion` can produce behind that reason, and
pin that a launcher that genuinely failed to resolve keeps its hint.