test(ha-commit-barrier-rollout): RED tests for classification totality (task 1.1)

New test_commit_barrier_rollout.c: per-type rows matching the VERIFIED
design table (STOP/RESUME/UPDATE/FAIL RETAIN per supersession), 13-value
totality sweep, fork/SIGABRT unknown-type fail-fast, fact-hook retention
contract against real persist+engine. wal_commit_mode_t + wal_classify
declared in persist.h; inert sentinel stub. 8/8 RED; suite baseline
zero preserved. Finding: RETAIN is registration-free (commit.c:233-239)
— observable contract documented in Implementation Notes.

src/controller/meson.build

@@ -121,6 +121,7 @@ controller_unit_test_src = [
   'testsuite/test_ha_rdhup_integration.c',
   'testsuite/test_ha_liveness.c',
   'testsuite/test_commit_engine.c',
+  'testsuite/test_commit_barrier_rollout.c',
   'commit.c',
   'startup_validation.c',
   'worker.c',