checkpoint: bug-851 root cause + raft TLA+ conformance spec family

Investigation & fixes (failover committed-job loss):
- root-cause bug-851 on an owned 3-node cluster: chaotic failover causes
  silent committed-prefix divergence (WAL hdr.term always 0; two leaders
  per term; no (term,lsn) reconcile). Evidence in repro-851/ + INVESTIGATION.
- live-validated fixes 848/849/850 (recovery-on-promotion, advertise real
  applied_lsn, persist-layer contiguity guard); add waldump WAL inspector.

Specs (strict raft.tla conformance — library owns the log):
- TLA-gap-analysis.md: impl vs raft/raft.tla, gaps G1-G6.
- raft-log-replication, raft-commit-safety, raft-sim-conformance: extend
  src/lib/raft to own log/commit/verification via callbacks (specs generated,
  cross-spec review passed).
- ha-term-safety: controller-side adapter + config marker (R1-R7); design done.
- config-upgrade-snapshot: R8 descoped here (deps entity-bearing-snapshots, bug-857).
- roadmap + buglog (851/854/857) + .wolf knowledge updated.

src/controller/testsuite/controller_test.c

@@ -63,6 +63,7 @@ extern void test_commit_durability(void);
 extern void test_ctrlstatus(void);
 extern void test_ha_heartbeat_committed(void);
 extern void test_ha_vote_floor_heartbeat(void);
+extern void test_waldump(void);
 
 void setUp(void) { return; }
 
@@ -195,6 +196,7 @@ int main(int argc, char* argv[])
     TEST(test_ctrlstatus);
     TEST(test_ha_heartbeat_committed);
     TEST(test_ha_vote_floor_heartbeat);
+    TEST(test_waldump);
 
     return UNITY_END();
 }