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

docker-compose.yml

@@ -483,7 +483,7 @@ services:
       # so ids survive container recreates and --scale still works.
       WORKER_ID: ${WORKER_ID:-}
       WORKER_STATE_DIR: ${WORKER_STATE_DIR:-/data/state}
-      WORKER_REGION: ${WORKER_REGION:-}
+      WARMBLY_NODE_REGION: ${WARMBLY_NODE_REGION:-}
       BOX_GOOGLE_CLIENT_ID: ${BOX_GOOGLE_CLIENT_ID:-}
       BOX_GOOGLE_CLIENT_SECRET: ${BOX_GOOGLE_CLIENT_SECRET:-}
       BOX_OUTLOOK_CLIENT_ID: ${BOX_OUTLOOK_CLIENT_ID:-}