docs(cctv): document the Toronto pack and the shared camera cap

Adds the Toronto settings to .env.example and a current-state section for the
pack, restores an approximate camera count in the README, and corrects the
claim that adding a pack never trims another region: with the shared
4,000-camera cap, the largest packs give way round-robin. Fixes two stale
comments about the list's refresh and the ground-height sidecar.

docs/CURRENT-STATE.md

@@ -977,7 +977,25 @@ id-hash fallback at low confidence.
 
 Once enabled, the 250 cameras nearest the five borough cores load.
 `CCTV_NYC_MAX_SOURCES` sets the pack cap (8–400). The catalog-wide ceiling stays at 4,000 and is shared
-round-robin, so adding this pack does not silently drop another region.
+round-robin: no region is dropped outright, but when the packs together exceed
+the ceiling, adding a pack trims cameras from the largest packs.
+
+## City of Toronto RESCU CCTV source pack
+
+The CCTV catalog adds the City of Toronto RESCU traffic cameras — downtown
+arterials plus the Gardiner, DVP, Allen and Lake Shore, which the Ontario 511
+pack does not cover. The server reads the keyless camera list the City
+publishes on its open data portal (`tmcearthcameras.json`, served as JSONP).
+The list has no URL field: frame URLs are built from each validated, digits-only
+camera number on the fixed origin
+`https://opendata.toronto.ca/transportation/tmc/rescucameraimages/CameraImages/`.
+The feed has no compass data, so headings are low-confidence priors. Some
+cameras return a 200 "Image Unavailable" placeholder frame instead of an error.
+
+By default all ~336 cameras load, nearest downtown first.
+`CCTV_TORONTO_MAX_SOURCES` sets the pack cap (8–500) and
+`CCTV_TORONTO_ENABLED=0` turns the pack off. The pack shares the 4,000
+catalog-wide ceiling round-robin with the other packs.
 
 ## DriveBC CCTV source pack