Task 3.1: when the sim publishes trace settings, sched_allocator() counts
job positions, starts a record for wanted jobs with their selection and
cluster-wide limits, pushes no-decision kinds as trace-only decisions,
and attaches the captured outcome to built decisions; every handoff
clears core->trace_rec. Live (trace_ctl NULL) is unchanged.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
