Adds two new fixtures spawning the real sched_job_picker/sched_allocator
thread pair directly against bare normal-mode and sim-mode core state
under genuine resource contention (2.0 capacity, 3 jobs x 1.0 demand),
asserting identical admission decisions and identical accounting state
(job->accounts, w->resInUse), with and without a matching host-scoped
limit. The pre-existing test_sim_contention_parity.c could not be reused
since its white-box stubs hard-code the old always-PEND behavior and
never exercise live election/allocation.
Confirms build_limit_vres_requests()/get_vres_value() (plugins/limit.c)
are #if 0'd dead code with zero live callers -- no limit in this codebase
currently gates/denies admission in either mode, only tracks/displays
usage -- so this proves usage-tracking parity, documented explicitly as
an honest scope boundary rather than a silent narrowing.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RLSNJhNoULvVcUhXEFafQC
