feat(scheduler-core): implement REPL breakpoints and state inspection (task 12.2)

Adds the interactive simulation REPL's breakpoint and state-inspection
commands (Req 5 AC 22): `break <event_type> [key=value ...]` / `info
break` / `delete <id>|all` on event and decision types, and `info
session/job/queue/worker/resource/summary`.

repl.c (370 lines after task 12.1) couldn't hold this task's full
surface under the project's 800-line cap, so it's split three ways
(matching the snapshot.c/snapshot_wire.c/snapshot_load.c precedent):
repl.c (execution control + dispatch), repl_break.c (matching/CRUD +
the three new driver-facing hooks), repl_info.c (info dumps), sharing
state via repl_internal.h. sim_loop.c gained 3 new bare hook calls
(repl.h inline wrappers, same pattern as task 12.1's two) at the
points design.md's pseudocode requires -- per decoded event before it
joins the batch, per session boundary, and per drained decision --
landing sim_loop.c at exactly 800/800 lines.

Two real bugs found and fixed during development (bug-1506, bug-1507):
an uninitialized xstr_table left breakpoint filter fields silently
NULL instead of failing loud, and repl_breakpoint_free() called a bare
free() on an RTTI-refcounted makeString() string, corrupting the heap.

Review found one gap: `info job` printed only a resreq presence flag
instead of the actual resreq text, when format_resreq() already
existed in this repo for exactly this purpose. Fixed to match.

Scheduler suite: 35/35 clean (was 34/34). RED-phase evidence (2 real
bugs plus 2 synthetic probes, all reverted with confirmed zero
residue) recorded in tasks.md.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JPPXeKSUXUqcqvzNXY1rzJ

src/scheduler/meson.build

@@ -19,6 +19,8 @@ scheduler_srcs = [
   'src/sim_verify.c',
   'src/sim_record.c',
   'src/repl.c',
+  'src/repl_break.c',
+  'src/repl_info.c',
   'src/schedobj.c',
   'src/plugin.c',
   'src/resource.c',
@@ -78,18 +80,23 @@ sched_core_isolation_lib = static_library(
 # Task 11.3 (scheduler-core spec, Req 5 AC 17): isolated compile target for
 # the simulation driver's own files, consumed by
 # testsuite/test_sim_isolation.c to prove at build time that
-# sim.c/sim_loop.c/sim_record.c/repl.c reference zero controller-facing
-# symbols (client/netio/xceapi/delay/idgen). All files are compiled together
-# into ONE archive -- task 11.2 added sim_loop.c as a sibling file to task
-# 11.1's sim.c, task 11.5 added sim_record.c as a third, and task 12.1 adds
-# repl.c as a fourth; covering only a subset of them would repeat core.c's
-# own siblings' (core_events.c/core_session.c/core_clock.c)
+# sim.c/sim_loop.c/sim_record.c/repl.c/repl_break.c/repl_info.c reference
+# zero controller-facing symbols (client/netio/xceapi/delay/idgen). All
+# files are compiled together into ONE archive -- task 11.2 added
+# sim_loop.c as a sibling file to task 11.1's sim.c, task 11.5 added
+# sim_record.c as a third, task 12.1 added repl.c as a fourth, and task
+# 12.2 adds repl_break.c/repl_info.c as a fifth/sixth (task 12.2's own
+# 800-line-cap split of repl.c's breakpoint/state-inspection logic --
+# repl_internal.h's own "Why a split at all" section has the full
+# rationale); covering only a subset of them would repeat core.c's own
+# siblings' (core_events.c/core_session.c/core_clock.c)
 # never-mechanically-covered gap for the sim driver. Same "compiling to an
 # object is enough, no real linking needed" rationale as
 # sched_core_isolation_lib above.
 sched_sim_isolation_lib = static_library(
     'sched_sim_isolation',
-    ['src/sim.c', 'src/sim_loop.c', 'src/sim_record.c', 'src/repl.c'],
+    ['src/sim.c', 'src/sim_loop.c', 'src/sim_record.c', 'src/repl.c',
+     'src/repl_break.c', 'src/repl_info.c'],
     include_directories: incdir,
     dependencies: scheduler_deps,
     install: false)