Go service that connects to aisstream.io websocket, filtered by MMSIs
from track_devices table. Writes positions to aisstream_pos (24h TTL)
and upserts latest position per vessel to aisstream_last. Reloads
MMSI list every 5 minutes to pick up changes.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
