feat(transit): add the TTC Toronto surface feed

TTC BusTime publishes keyless GTFS-Realtime VehiclePositions with real
coordinates for the surface network: ~1,180 buses and streetcars with
bearing and per-vehicle timestamps. Registering it is one registry row.

The subway is deliberately absent. BusTime covers surface vehicles only
and the subway publishes no positions, so Lines 1/2/4 are left out rather
than inferred from schedules — the same rule that keeps NYCT out.

Route numbers establish the mode: the three-digit 500-series is streetcar,
as are the four Blue Night routes on streetcar trackage. A leading 5 alone
would misclassify bus routes 50-59, so the rule is anchored and tested.

Licensing is the portal-wide Open Government Licence - Toronto; the CKAN
record for the BusTime NVAS dataset leaves its own licence field blank,
and the terms note says so rather than overstating the grant.

Refs #70

docs/CURRENT-STATE.md

@@ -3659,8 +3659,9 @@ Transit is off by default, and share links use token `j`. The movement panel ord
 places Transit directly after Street Traffic and before Bike Share. Cameras and
 utilities retain their own groups. The layer polls
 registered feeds near the camera every 15 seconds, below a 3,000 km altitude
-gate. Seven keyless regions are available: Boston, Austin, Minneapolis–St Paul,
-Helsinki, the Netherlands, Norway and South East Queensland. Mode silhouettes
+gate. Eight keyless regions are available: Boston, Austin, Minneapolis–St Paul,
+Helsinki, the Netherlands, Norway, South East Queensland and Toronto (TTC
+surface vehicles; the subway publishes no positions). Mode silhouettes
 identify buses, trams, subways, trains, ferries and unclassified vehicles.
 
 Retained transit history uses the same outlier quarantine as live observations and