feat: settle on WARMBLY_NODE_REGION as the one region variable for every role, because the join script wrote it while the worker still read WORKER_REGION, so a joined worker reported no region and the placement geography term stayed dead for exactly the machines that had been given one

cmd/worker/main.go

@@ -239,7 +239,7 @@ func newNodeAgent(workerID uuid.UUID, bindIP string) *nodeagent.Agent {
 		NodeID:  workerID,
 		Role:    models.NodeRoleWorker,
 		Name:    os.Getenv("WARMBLY_NODE_NAME"),
-		Region:  os.Getenv("WORKER_REGION"),
+		Region:  nodeRegion(),
 		Address: reportedIP,
 		Version: buildVersion(),
 		BaseURL: os.Getenv("ENCRYPTED_KEYS_BACKEND_URL"),
@@ -249,6 +249,17 @@ func newNodeAgent(workerID uuid.UUID, bindIP string) *nodeagent.Agent {
 	})
 }
 
+// nodeRegion reads the sign-in geography hint. WARMBLY_NODE_REGION is what the
+// join script writes and what every role uses; WORKER_REGION is the older
+// worker-only name, kept as a fallback so a machine configured by hand before
+// the join flow existed keeps reporting its region.
+func nodeRegion() string {
+	if v := os.Getenv("WARMBLY_NODE_REGION"); v != "" {
+		return v
+	}
+	return os.Getenv("WORKER_REGION")
+}
+
 // buildVersion is the image tag this build reports. Set by the join script
 // from the tag it pulled; empty means unknown, which the control plane must
 // not read as "needs updating".