feat(raft-apply-decoupling): extract guarded fact transition logic into reusable cores (task 2.1)

Split mark_job_start/finish/fail/update in job.c into four hook-free
core functions (apply_job_*_transition) containing only the
monotonic-rank guard and mutation. Wrappers now peek the same guard
to decide hook-firing, then delegate to the core, preserving exact
pre-extraction hook-firing timing. Prerequisite for task 2.2's
apply_committed_entry() dispatch and the ordered apply pump (6.1).

src/controller/testsuite/controller_test.c

@@ -77,6 +77,7 @@ extern void test_ha_dispatch_integration(void);
 extern void test_ha_core_safety(void);
 extern void test_ha_partition(void);
 extern void test_persist_snapshot_entities(void);
+extern void test_apply_seam(void);
 
 void setUp(void) { return; }
 
@@ -223,6 +224,7 @@ int main(int argc, char* argv[])
     TEST(test_ha_core_safety);
     TEST(test_ha_partition);
     TEST(test_persist_snapshot_entities);
+    TEST(test_apply_seam);
 
     return UNITY_END();
 }