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/testsuite/meson.build

@@ -551,6 +551,15 @@ sched_sim_isolation_test = executable(
              '-DXCE_SIM_REPL_H_PATH="'
              + (meson.current_source_dir() / '..' / 'include' / 'repl.h')
              + '"',
+             '-DXCE_SIM_REPL_BREAK_C_PATH="'
+             + (meson.current_source_dir() / '..' / 'src' / 'repl_break.c')
+             + '"',
+             '-DXCE_SIM_REPL_INFO_C_PATH="'
+             + (meson.current_source_dir() / '..' / 'src' / 'repl_info.c')
+             + '"',
+             '-DXCE_SIM_REPL_INTERNAL_H_PATH="'
+             + (meson.current_source_dir() / '..' / 'src' / 'repl_internal.h')
+             + '"',
              '-DXCE_SIM_LIB_PATH="'
              + sched_sim_isolation_lib.full_path()
              + '"'],
@@ -660,7 +669,13 @@ sched_sim_equivalence_test = executable(
 # (core.c, core_clock.c, core_events.c, core_session.c, decision.c, plugin.c,
 # plugins/builtin_fcfs.c, recording.c, recording_session.c, sim.c, sim_loop.c,
 # sim_record.c, sim_verify.c, snapshot.c/snapshot_wire.c/snapshot_load.c) PLUS
-# the new ../src/repl.c under test. Needs libedit_dep (parent meson.build)
+# ../src/repl.c under test. Also pulls in ../src/repl_break.c/repl_info.c
+# (task 12.2's 800-line-cap split of repl.c -- repl_internal.h's own "Why a
+# split at all") -- required at link time since sim_loop.c's new breakpoint
+# hooks (repl.h) reference symbols repl_break.c defines, even though this
+# file's own tests exercise only the execution-control slice; task 12.2's
+# own breakpoint/inspection tests live in the sibling
+# test_repl_breakpoints_inspection.c. Needs libedit_dep (parent meson.build)
 # at link time -- repl.c's real readline()/add_history() calls are pulled
 # into this TU by the white-box #include.
 sched_repl_execution_control_test = executable(
@@ -670,6 +685,29 @@ sched_repl_execution_control_test = executable(
     dependencies: [scheduler_test_deps, libedit_dep],
     install: false)
 
+# Contract test for the interactive simulation REPL's breakpoint and
+# state-inspection slice (scheduler-core spec, task 12.2, Req 5 AC 22
+# "Breakpoints"/"State inspection"): setting a breakpoint on a specific
+# event type and field value pauses the REPL exactly when a matching event
+# is about to be processed, and each `info` command reports state matching
+# a snapshot dump of the same moment. Same white-box #include pattern as
+# sched_repl_execution_control_test above (core.c, core_clock.c,
+# core_events.c, core_session.c, decision.c, plugin.c,
+# plugins/builtin_fcfs.c, recording.c, recording_session.c, sim.c,
+# sim_loop.c, sim_record.c, sim_verify.c,
+# snapshot.c/snapshot_wire.c/snapshot_load.c, repl.c, repl_break.c,
+# repl_info.c). Split into its own file rather than appended to
+# test_repl_execution_control.c -- that file was already 644 lines after
+# task 12.1, and this task's own fixture/assertion surface (breakpoints on
+# multiple event kinds plus five separate `info` dumps) does not fit
+# alongside it under this project's 800-line cap.
+sched_repl_breakpoints_inspection_test = executable(
+    'sched_repl_breakpoints_inspection_test',
+    ['test_repl_breakpoints_inspection.c'],
+    include_directories:[incdir],
+    dependencies: [scheduler_test_deps, libedit_dep],
+    install: false)
+
 # Register as meson tests so `meson test --suite scheduler` runs them all.
 # detect_leaks=0 matches the suite convention (fixtures are not torn down).
 test('scheduler test', scheduler_test, suite: 'scheduler',
@@ -763,3 +801,6 @@ test('scheduler sim equivalence test',
 test('scheduler repl execution control test',
      sched_repl_execution_control_test, suite: 'scheduler',
      env: ['ASAN_OPTIONS=detect_leaks=0'])
+test('scheduler repl breakpoints inspection test',
+     sched_repl_breakpoints_inspection_test, suite: 'scheduler',
+     env: ['ASAN_OPTIONS=detect_leaks=0'])