moving trains/boats

[damiante]

maps that have train tracks should have trains that periodically go through on the tracks
maps that have waterways should have boats that periodically go along the water

[baely]

Splitting this in two:

• Trains: doable now. Train tracks exist in the Palace, Inaka and both station maps, and train sprites already exist from the travel cutscene. Plan: ambient trains that periodically run along the tracks in those maps (spawn off-screen, cross, despawn).
• Boats: blocked on assets — no boat sprites exist, and current water is decorative ponds rather than waterways. Leaving boats out until there's art and a map with an actual waterway; that half can become its own issue then.

Queued — implementing the trains half, committing to master.

[baely]

Trains half is done on master (1177142): rooms whose map has train-track tiles (Palace, Inaka) get an ambient train that periodically enters off-screen, runs the full track and leaves — random livery and direction, every 15–40 seconds. Station tracks are excluded since the parked boarding train lives there. Leaving this open for the boats half, which is still blocked on boat art and a map with an actual waterway.