feat: wire persist_init/recover/start/stop into cluster lifecycle (P0-F)

- Add `persist_t persist` field to cluster_t (cluster_def.h includes persist.h)
- Add `workdir` and `name` fields to myconf_t; main.c passes them through
- cluster_init: call persist_set_workdir, persist_init, persist_recover after apiserver_init
- cluster_start: call persist_start (launches fsync thread + registers WAL hooks)
- cluster_fini: call persist_stop + persist_fini before delaymgr/vtaskmgr teardown
- persist_init: store cluster back-pointer (replaces (void)c stub)
- persist_start: register persist_job/queue/worker_hook_fun via xce_add_hook when cluster != NULL
- Add test_cluster_persist.c: compile-time struct check + config defaults + workdir path derivation
- Register test in controller_test.c and meson.build

All controller tests pass (1/1 OK, 50s).

src/controller/cluster.c

@@ -610,6 +610,28 @@ int cluster_init(cluster_t* c)
 
     apiserver_init(c);
 
+    /* Persistence: derive paths, init, and recover from WAL/snapshot */
+    {
+        const char*      workdir = c->myconf->workdir ? c->myconf->workdir
+                                                      : DEFAULT_WORKDIR;
+        const char*      name    = c->myconf->name    ? c->myconf->name
+                                                      : "controller";
+        persist_config_t pcfg    = persist_config_defaults();
+
+        persist_set_workdir(&c->persist, workdir, name);
+        rc = persist_init(&c->persist, &pcfg, c);
+        if (rc != 0) {
+            ERROR("persist_init failed: %d", rc);
+            return rc;
+        }
+        rc = persist_recover(&c->persist);
+        if (rc != 0) {
+            ERROR("persist_recover failed: %d", rc);
+            persist_fini(&c->persist);
+            return rc;
+        }
+    }
+
     xce_run_hooks(&(c->hooksys), XCE_CONTROLLER_HOOK_CLUSTER, HOOK_AFTER_EVENT,
                   HOOK_DETAIL_CLUSTER_INIT, c);
 
@@ -758,6 +780,13 @@ int cluster_start(cluster_t* c)
     vtaskmgr_start(&(c->vtaskmgr));
     delaymgr_start(&(c->delaymgr));
 
+    /* Start persistence fsync thread and register WAL hooks */
+    rc = persist_start(&c->persist);
+    if (rc != 0) {
+        ERROR("persist_start failed: %d", rc);
+        return rc;
+    }
+
     delay_task(&(c->delaymgr), c->myconf->cluster_config->heartbeat_interval,
                -1, (delay_task_entry_fn_t)check_workers_timeout, (void*)c);
 
@@ -790,6 +819,10 @@ int cluster_run(cluster_t* c)
 
 void cluster_fini(cluster_t* c)
 {
+    /* Stop persistence before tearing down the rest */
+    persist_stop(&c->persist);
+    persist_fini(&c->persist);
+
     delaymgr_fini(&(c->delaymgr));
     vtaskmgr_fini(&(c->vtaskmgr));
     endpoint_fini(&(c->ep));