feat(cctv): add the City of Toronto RESCU camera pack

The province's 511 pack covers Ontario's highways; this adds the municipal
network underneath it — roughly 336 cameras across downtown arterials plus
the Gardiner, DVP, Allen and Lake Shore, from the City's own open data.

The list is keyless and carries no frame URL, so frame URLs are built from
the convention the dataset documents (`CameraImages/loc####.jpg`) and a
camera number validated as plain digits. The frame proxy is therefore
pinned to the portal origin by construction rather than by trusting a
field. The list fetch refuses redirects, bounds the body it buffers, and
releases the transport on every rejection path.

The dataset publishes no camera facing. `D1`-`D4` look like a compass and
map trivially onto one, but they describe the *comparison* images — static
reference stills captured in 2016 and served from a different path — not
the live pan-tilt-zoom frame. A heading derived from them would be
confidently wrong for every camera in the city, so every camera takes the
shared id-hash fallback at low confidence, as headingless Austin, TfL,
Fintraffic and Calgary cameras do. A test pins that down so it is not
"fixed" later.

Names stay verbatim: the feed's labels are upper-case, and title-casing
would mangle MCCOWAN RD and ST HELEN'S AVE more often than it helped.

Carries the Open Government Licence – Toronto attribution the licence
requires. Disable with `CCTV_TORONTO_ENABLED=0`.

server/providers/cctv/constants.js

@@ -275,6 +275,38 @@ export const DELDOT_ANCHORS = [
   { lat: 39.1582, lon: -75.5244 }, // Dover (Kent)
   { lat: 38.6906, lon: -75.3877 }, // Georgetown (Sussex)
 ];
+/**
+ * City of Toronto RESCU traffic cameras: the municipal network the province's
+ * 511 pack does not cover — downtown arterials plus the Gardiner, DVP, Allen
+ * and Lake Shore. One keyless list for the whole city (~336 cameras), from the
+ * City's open data portal, refreshed within two minutes of any change.
+ *
+ * The list is served as JSONP (`jsonTMCEarthCamerasCallback({...})`); the
+ * portal publishes the same data as .xml and .csv beside it.
+ */
+export const TORONTO_RESCU_LIST_URL =
+  'https://opendata.toronto.ca/transportation/tmc/rescucameraimages/Data/tmcearthcameras.json';
+/**
+ * The only origin Toronto camera frames may come from. The list carries no URL
+ * field: frame URLs are BUILT from this origin and a strictly-digits camera
+ * number (`loc####.jpg`, the convention the dataset documents), so no upstream
+ * field can steer the frame proxy off-host.
+ */
+export const TORONTO_RESCU_IMAGE_ORIGIN =
+  'https://opendata.toronto.ca/transportation/tmc/rescucameraimages/CameraImages/';
+/** The whole city fits under this; the cap exists to stay tunable, not to trim. */
+export const DEFAULT_TORONTO_MAX_SOURCES = 336;
+/** Yonge / Queen: the prioritization anchor. */
+export const TORONTO_DOWNTOWN = { lat: 43.6532, lon: -79.3832 };
+/** Toronto's lakeshore core sits near 76 m; the ravines and the north of the
+ * city run higher. This prior only has to be close — the client's one-shot
+ * ground snap corrects it wherever 3D tiles are loaded. */
+export const TORONTO_GROUND_ELEVATION_M = 90;
+/** Hard ceiling on the RESCU list body. The whole city is ~336 rows and under
+ * 60 KB; this only exists so an upstream that streams an unbounded body cannot
+ * be buffered without limit. */
+export const TORONTO_MAX_CATALOG_BYTES = 4 * 1024 * 1024;
+
 /** Camera CATALOGS change rarely; 15 min keeps multi-megabyte upstream list refetches (Austin rows.json + 4 Caltrans districts + TfL + Ontario 511) infrequent. Frames are fetched per-request and are unaffected. */
 export const CCTV_SOURCE_CACHE_MS = 15 * 60 * 1000;
 /** Per-provider catalog-fetch timeout. Bounds the worst-case refresh so one