Merge current main into HAL-522 review candidate

CHANGELOG.md

@@ -1,5 +1,16 @@
 # Changelog
 
+- Add New York City traffic cameras from the NYC DOT Traffic Management Center
+  as an opt-in CCTV pack. NYC DOT requires a data-sharing agreement for the
+  camera feed, so the pack is off unless `CCTV_NYC_ENABLED=1` is set by an
+  operator who holds one; otherwise no request reaches NYC DOT. NYC DOT's
+  requested disclaimer is in the Data attribution popover. The camera list is one keyless JSON request to
+  `webcams.nyctmc.org/api/cameras`; frames are stills synthesized from each
+  camera UUID on that same host, so a catalog field cannot steer the proxy
+  off-host. Offline cameras are dropped. Once enabled, the 250 cameras nearest
+  the five borough cores load and `CCTV_NYC_MAX_SOURCES` changes the cap. The catalog-wide ceiling is
+  unchanged; extra cameras share it round-robin with the other packs.
+
 - Treat explicitly current, complete empty vessel coverage as a successful update,
   clearing obsolete contacts while retaining stale or incomplete snapshots.
 
@@ -117,6 +128,28 @@
   says when the transponder was last heard, so answers read "broadcasting
   squawk 7700" or "ADS-B reports general emergency". No new source or
   request: OpenSky already carries the squawk and adsb.lol carries both.
+- Street Level: KartaView is the third provider, keyless. Light its chip
+  (purple; off by default, one provider at a time) and zoom in below about
+  6 km: the lines are the streets KartaView has photos of (z13–14 tiles from
+  `api.kartaview.org`). A click on a line opens the photo nearest the click
+  without moving the camera, flat or 360° (a small WebGL panorama: drag to
+  look, wheel to zoom), with cones along its drive and ‹ › / ← → to step
+  through it. The caption links to the full-size photo (KartaView's photo
+  pages fail for signed-out visitors), and the globe credits "© KartaView
+  contributors, CC BY-SA 4.0". Share links carry it in the provider
+  switches (`0.m.0_0.r.google-0*kartaview-1`). Archived photos (KartaView
+  answers 409) are skipped by the click and by ‹ ›. Shift+← →, ↑ ↓, + − and
+  pinch look around a 360° photo. The open photo's marker is a purple view
+  cone pointing along the drive (KartaView's own compass headings are often
+  0 or far off). The IMAGERY (ALL / 360° / FLAT) and SINCE filters apply to
+  KartaView as to Mapillary: its lines are filtered by KartaView's own
+  server (its filtered PNG tiles, as a mask over the JSON lines), and the
+  photo a click opens, and the cones, by each photo's projection and upload
+  date. KartaView's SINCE is the upload date (all its server can filter by);
+  a note under the slider says so while KartaView is lit (`sinceBasis:
+  'upload'` in the provider contract).
+  Mapillary's line coverage and sequence cones are now shared by both
+  (`lineCoverage.js`, `sequenceCones.js`).
 
 - Street Level: Google Street View is the second provider. On the Google 3D
   map (Google's terms keep it off other maps), light its chip (off by