docs(notebook): add OGC API – Moving Features tutorial with executed outputs

tutorial.ipynb walks through the eight core MobilityAPI endpoints
(DELETE/POST collection, POST/GET items, bbox spatial filter, tgsequence,
velocity, subTrajectory) end-to-end against the Danish Maritime
Authority AIS dataset, with matplotlib + contextily visualisations:

- All-vessels overview map (brown trajectories on CartoDB Positron)
- BBox-filtered map with Rødby harbour envelope on OpenStreetMap
- Multi-vessel velocity profile comparison with a 10-knot speed-limit
  reference line and shaded violation zone
- Subtrajectory result summary table (DataFrame)
- Green-over-brown subtrajectory overlay against full trajectories

Outputs committed inline (14/17 code cells have rendered outputs:
image/png, text/html, stream) so the notebook renders fully on GitHub
without a server. Two conceptual figures bundled under doc/images:

- ogc-moving-features-class-diagram.png — OGC standard figure 1
- mobilityapi-backing-schema.png — the PostgreSQL schema MobilityAPI
  creates on first POST (collections, moving_features,
  temporal_geometries, temporal_properties, temporal_values)

README gains a one-line pointer to tutorial.ipynb under Usage.

Author: estebanzimanyi

README.md

@@ -74,6 +74,8 @@ If you need the AIS dataset, download `aisdk_2024-08-07.zip` from the [Danish Ma
 
 Send HTTP requests to the API using any HTTP client. As an example, the `ais.sql` script will create `ships` and `ship2` tables containing ships data — change the CSV path in the script to point at your downloaded dataset.
 
+For a guided walk-through of the OGC API – Moving Features endpoints against the Danish AIS dataset, open the [`tutorial.ipynb`](tutorial.ipynb) notebook (start the server with `./run.sh` first).
+
 ## Where MobilityAPI fits
 
 MobilityAPI is the HTTP / OGC layer of the MEOS ecosystem. The other layers are: