replay_wal() now halts logical apply and engages persist_mark_apply_resource_fenced()
on a negative apply_committed_entry() return during boot/restart replay, mirroring
persist_apply_pump_run()'s existing live-path halt-and-fence behavior (task 4.1).
Physical scan bookkeeping (current_lsn, CRC chain) stays unconditional per entry,
consistent with persist_recover()'s own established current_lsn/last_applied_lsn
divergence precedent.
Went through one remediation round: round 1 exercised the wrong ha.c gate (periodic
re-alert timer); round 2 corrected the test to drive the real election-time gate
(raft_cb_become_leader_with_cluster_for_test()), with teeth independently confirmed
via a temporary fence-clear RED/GREEN cycle. Round-2 reviewer APPROVED.
Documents a real, NOT-fixed residual gap found during this task: a node's very
first-ever promotion evaluation in a fresh process runs before that node's own
first persist_recover()/replay_wal() call, so this fence is invisible to that one
promotion check (ha.c:1303-1408 gate runs before ha.c:1427-1439's first-boot
recovery). Every promotion evaluation after a process's first one is protected.
Out of this task's persist.c-only boundary; flagged for a dedicated ha.c follow-up.