test(ha-commit-engine): RED integration tests for ACK feed and sync-append (task 5.1)

Tests 30-34: wired repl_on_ack feeds engine, membership mutators
trigger re-evaluation, per-entry sync-append contract (stale-ACK
rejection, committed_lsn unmoved on timeout, n_peers=1 replaces
-ENODEV). test_repl_majority walAck cases rewired to per-LSN
semantics (configAck byte-identical). Sanctioned scaffolding:
entry_lsn param on repl_wait_majority_ack (legacy body byte-identical,
callers pass 0), inert repl_set_commit_engine stub. 9 RED failures;
baseline signatures unchanged. LSN-0 edge documented for 5.2/5.3.

src/controller/config_repl.c

@@ -913,7 +913,9 @@ int push_config_to_standbys(cluster_t *c, const uint8_t *bytes, size_t blen,
 
     /* Req 8.1–8.3: wait for majority-quorum OP_upgradeConfigAck.
      * On quorum: advance committed_config_tag atomically (Req 8.5). */
-    int rc = repl_wait_majority_ack(&c->persist.repl, CONF_PUSH_TIMEOUT_MS,
+    /* entry_lsn = 0: the configAck branch ignores it (walAck-only adapter
+     * parameter, ha-commit-engine task 5.1). */
+    int rc = repl_wait_majority_ack(&c->persist.repl, 0, CONF_PUSH_TIMEOUT_MS,
                                     (uint8_t)OPCode_upgradeConfigAck);
     if (rc == 0) {
         atomic_store_explicit(&c->ha.committed_config_tag, new_tag,