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`.

src/data/dataCredits.js

@@ -247,6 +247,12 @@ export const DATA_CREDITS = [
       '<a href="https://data.norge.no/nlod/en/2.0" target="_blank" rel="noopener">Norwegian licence for Open Government data (NLOD)</a> ' +
       'distributed by Statens vegvesen',
   },
+  {
+    key: 'toronto-cctv',
+    html:
+      'Traffic cameras (Toronto): contains information licensed under the ' +
+      '<a href="https://www.toronto.ca/city-government/data-research-maps/open-data/open-data-licence/" target="_blank" rel="noopener">Open Government Licence – Toronto</a>',
+  },
   {
     key: 'gbfs',
     html: 'Bikeshare availability: GBFS operator feeds (e.g. Austin BCycle)',