feat(scheduler-core): implement simulation decision verification (task 11.4)

Add sim_verify.c (sim_decision_eq/sim_log_mismatch: real structural
comparison of dispatch/pend decision payloads, not a jobid shortcut) and
wire it into sim_loop.c's ReplaySession drain loop via decode_ReplaySession_ptr()
(first real consumer of the generated capnp decode path). --sim-verify now
detects and reports genuine decision divergence with logical-time + detail,
per Req 5 AC 15/18.

src/scheduler/meson.build

@@ -16,6 +16,7 @@ scheduler_srcs = [
   'src/recording_session.c',
   'src/sim.c',
   'src/sim_loop.c',
+  'src/sim_verify.c',
   'src/schedobj.c',
   'src/plugin.c',
   'src/resource.c',