Integrate with a Signal K marine data server via REST and WebSocket

Steps

1. Query GET /signalk on the target server to discover supported spec versions and their signalk-http/signalk-ws endpoint URLs rather than hardcoding a version path
2. If the server requires auth, POST credentials to /signalk/{version}/auth/login to receive an access token, or pre-generate one with the signalk-generate-token CLI, then send it as Authorization: Bearer {token} per the Signal K security spec
3. Poll the current full-model JSON via GET /signalk/v1/api/vessels/self/... for one-off reads
4. Open a WebSocket at /signalk/v1/stream?subscribe=self (or subscribe=all for fleet/AIS targets) and handle the initial hello message before processing streaming delta updates
5. For historical data use the optional /signalk/v1/snapshot REST endpoint or /signalk/v1/playback WebSocket with startTime and playbackRate parameters
6. To extend server behavior, write a Node.js plugin exporting start/stop functions and install it under the server's plugin directory, using the provided ServerAPI app object to register custom routes or resource providers