feat(scheduler-sim-decision-trace): parse the trace command and manage trace settings

Task 4.3: trace on all|job SEL... [level] [lines N] [file PATH], off and
status, parsed from the raw line; invalid arguments are named and leave
the settings unchanged; refcounted next/current settings; status shows
the settings in effect or pending, whole arrays as <base>[*], and stored
trace memory against its bound.

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

src/scheduler/meson.build

@@ -32,6 +32,7 @@ scheduler_srcs = [
   'src/repl_trace_render.c',
   'src/repl_trace_render_outcome.c',
   'src/repl_trace_store.c',
+  'src/repl_trace.c',
   'src/schedobj.c',
   'src/plugin.c',
   'src/resource.c',