R-270: the local_api drift detector also names a TOKEN-only divergence

A rotation that reached bootstrap.json but not controller.yaml left the
agent channel at 401 across restarts while the endpoint-only detector
stayed silent. The tokens are now compared (constant time, boolean only);
the token case gets its own banner key and operator message. Still
detection only - nothing is reconciled (R-78).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

controller/cmd/controller/main.go

@@ -2010,12 +2010,13 @@ func main() {
 	// local_api endpoint drift (R-77, from the 2026-07-25 outage): controller.yaml and bootstrap.json
 	// can disagree indefinitely and silently — the island migration rewrote the latter and the
 	// controller kept dialling the former for 17.5 h, alerting only "agent unreachable". This NAMES
-	// the fault; it deliberately does not reconcile the files (R-78 owns which one wins).
+	// the fault; it deliberately does not reconcile the files (R-78 owns which one wins). Since R-270 it
+	// also names a TOKEN-only divergence (a rotation that reached bootstrap.json only).
 	//
 	// Startup-only is sufficient and correct: both files are read at boot and neither changes under a
 	// running controller, so a periodic re-check would add noise without adding signal.
 	if d := bootstrap.DetectEndpointDrift(*configPath, cfg, logger); d != nil {
-		alertMgr.SetEndpointDriftAlert(true, "alert.endpoint_drift", d.HungarianMessage())
+		alertMgr.SetEndpointDriftAlert(true, d.AlertKey(), d.HungarianMessage())
 		if notifier != nil {
 			notifier.NotifyEndpointDrift(d.EnglishMessage(), d.FingerprintAgrees)
 		}