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.

src/data/dataCredits.js

@@ -201,6 +201,15 @@ export const DATA_CREDITS = [
       'Traffic cameras (Calgary): contains information licensed under the ' +
       '<a href="https://data.calgary.ca/stories/s/Open-Calgary-Terms-of-Use/u45n-7awa" target="_blank" rel="noopener">Open Government Licence – City of Calgary</a>',
   },
+  {
+    key: 'kingcounty-cctv',
+    html:
+      'CCTV cameras &amp; frames (King County, WA): King County Road Services — ' +
+      '<a href="https://kingcounty.gov/en/dept/local-services/roads" target="_blank" rel="noopener">kingcounty.gov</a>, ' +
+      'per the ' +
+      '<a href="https://kingcounty.gov/en/dept/kcit/data-information-services/gis-center/about/terms-conditions-copyrights" target="_blank" rel="noopener">KCGIS Center terms</a>. ' +
+      'A few cameras are supplied by partner cities (Redmond, Sammamish, Newcastle, Snoqualmie); each names its owner in the CCTV panel.',
+  },
   {
     key: 'gbfs',
     html: 'Bikeshare availability: GBFS operator feeds (e.g. Austin BCycle)',