pin internal/meta's hyperhive on the controller's rev and rebuild agents when it moves

The swarm controller offers its own running rev (services.hyperhive.c0re.
hyperhiveRev) as the hyperhive pin of internal/meta and takes it only when
the forge compare API shows it descends from the committed pin; merges to
hyperhive main no longer move the pin, and the first commit pins main's head.
When a commit moves the pin, every placed agent gets a TriggerDeploy.

A deploy after a meta update no longer waits on it succeeding (after_any), so
a down builder does not hold back hives that render locally.

swarm-controller/src/startup.rs

@@ -285,8 +285,9 @@ fn spawn_forge_workers(
     auth: Option<Arc<auth::AuthBridge>>,
     queue: Option<async_nats::Client>,
 ) {
-    // `internal/meta` appears, and catches up with every head that moved while
-    // this daemon was down.
+    // `internal/meta` appears, catches up with every config head that moved
+    // while this daemon was down, and takes this daemon's rev as the hyperhive
+    // pin when that is newer.
     if let Err(e) = crate::jobq::queue_meta_update(jobq) {
         tracing::warn!(error = %format!("{e:#}"), "update_meta: queueing failed");
     }