docs(spec): libxce-alloc-preason-equality review fixes; new scheduler-sim-discrete-clock spec

libxce-alloc-preason-equality (requirements, design, tasks; not yet approved):
- alloc_eq compares `from` and excludes only instid; the scheduler stamps
  `from` with the deciding session's start, the same clock reading that
  is recorded as beginRound, so a replay reproduces it.
- every comparator takes an optional char** why: a malloc'd description
  of the first difference, owned and freed by the caller; --sim-verify
  mismatch lines print it (resolves bug-1881).
- job_preason_eq is new full-match behavior, not a relocation (bug-1845
  keeps the simulator main-reason-only); the three white-box test files
  switch to it and keep their sim_verify.c include.
- alloc_eq stays separate from merge_job_alloc()'s same_alloc_slot()
  (bug-1863), which does match on instid.

scheduler-sim-discrete-clock (initialized): remove --sim-speed so the
simulator clock moves only at recorded timestamps and a replayed
session_start equals the recorded beginRound exactly.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

.kiro/specs/libxce-alloc-preason-equality/spec.json

@@ -1,7 +1,7 @@
 {
   "feature_name": "libxce-alloc-preason-equality",
   "created_at": "2026-09-24T04:42:20Z",
-  "updated_at": "2026-09-24T05:12:00Z",
+  "updated_at": "2026-09-28T08:40:00Z",
   "language": "en",
   "phase": "tasks-generated",
   "approvals": {