A node's worker label is worker, so a device is only a paired one

- NodeDef `device`/`device_policy` become `worker`/`worker_policy`, the
  issue `ignored_device` becomes `ignored_worker`, and the SDK's `@node`
  takes `worker=` and `worker_policy=`
- FlowStore._migrate renames the keys in published and draft documents
  once, bumping their version; a queued run's `needs` reads the old key
- placement passes the label as `label`, client regenerated
- docs: worker placement wording, MCP issuer without DOMAIN, device rows in
  the CLI data directory and the API table, device links in compose comments

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docker/compose.lan.yml

@@ -10,7 +10,7 @@ services:
     ports: !override
       - "${APP_PORT:-8080}:8000"
     environment:
-      # The address the instance gives out: the link the Panels dialog shows a
+      # The address the instance gives out: the link a device's page shows a
       # screen and the one its emails carry. app.${DOMAIN} resolves on this host
       # only, so `make dev-lan` passes the published port on the LAN address.
       - FRONTEND_HOST=${LAN_URL:-http://app.${DOMAIN:-localhost}}