feat(cctv): King County road camera source pack (Washington State)

Adds King County DOT Road Services' cameras as a keyless source pack, from
the county's public ArcGIS FeatureServer layer ("King County and WSDOT
Traffic Cameras"). 59 live cameras against the current feed.

- The `outFields` list is explicit on purpose: the layer also carries
  asset-administration columns (including staff names) that must never be
  fetched.
- Only live, active cameras with frames on the county's own
  info.kingcounty.gov image handler are registered; the feed writes http://
  and the handler serves HTTPS, so URLs are upgraded and pinned before
  registration. WSDOT-owned rows are skipped so a camera never appears twice
  when a statewide WSDOT pack is present; the few city-owned cameras the
  county hosts (Redmond, Sammamish, Newcastle, Snoqualmie) carry their owner
  as the per-camera credit, DriveBC-style.
- The layer publishes no facing: headings use the shared id-hash fallback at
  low confidence, correctable with the calibration gizmo.
- Uniquely among the packs, the county publishes each camera's hardware
  Manufacturer/Model (Cohu 3950/3965, Bosch AUTODOME IP 5000i, Axis
  Q6135-LE, Siqura PD910). The model string is whitespace-collapsed (the
  feed carries stray newlines) and carried on the source as `model`, with an
  additive passthrough in normalizeSourceItem (same pattern as poseSource)
  so identified-hardware consumers can use it. All 59 live cameras carry a
  model value.
- Attribution per the KCGIS Center terms, registered in the attribution
  popover and documented in DATA_SOURCES.md.
- Defaults: the whole catalog loads (125 cap); CCTV_KINGCOUNTY_MAX_SOURCES
  changes the cap, CCTV_KINGCOUNTY_ENABLED=0 turns the pack off.
- Tests: filtering (owner/live/status/host/geometry/bbox), HTTPS upgrade,
  model whitespace-collapse and passthrough, partner-city credit, env cap,
  upstream-failure fallback, and normalizeSourceItem model semantics.

server/providers/cctv/constants.js

@@ -244,6 +244,25 @@ export const DELDOT_ANCHORS = [
   { lat: 39.1582, lon: -75.5244 }, // Dover (Kent)
   { lat: 38.6906, lon: -75.3877 }, // Georgetown (Sussex)
 ];
+
+/** King County, WA road cameras: keyless public ArcGIS FeatureServer layer
+ * ("King County and WSDOT Traffic Cameras", King County DOT Road Services).
+ * GeoJSON with WGS84 point geometry. `outFields` is an explicit list on
+ * purpose: the layer also carries asset-administration columns (including
+ * staff names in `ModifiedBy`) that must never be fetched. Uniquely among the
+ * packs, the county publishes each camera's hardware `Manufacturer`/`Model`
+ * (Cohu 3950/3965, Bosch AUTODOME, Axis Q6135-LE, …), carried through as the
+ * source's `model`. */
+export const KING_COUNTY_CAMERAS_URL =
+  'https://services.arcgis.com/Ej0PsM5Aw677QF1W/arcgis/rest/services/TRAFFICCAMERA_POINT_2029/FeatureServer/0/query?where=1%3D1&outFields=AssetID,Location,Description,ImageURL,CamRegion,Live,Model,Manufacturer,Owner,CurrentStatus&f=geojson';
+/** Frames come only from the county's own image handler host. */
+export const KING_COUNTY_IMAGE_ORIGIN = 'https://info.kingcounty.gov/';
+/** The whole catalog is ~125 rows (~59 live county cameras); no thinning by
+ * default. */
+export const DEFAULT_KING_COUNTY_MAX_SOURCES = 125;
+/** Prioritization anchor: Renton, roughly central to the county road network. */
+export const KING_COUNTY_ANCHORS = [{ lat: 47.4829, lon: -122.2171 }];
+
 /** 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