fix(cctv): serve King County model/manufacturer through /api/cctv/sources

The loader and normalizer carried the hardware model, but the /sources
response projection and the browser catalog both whitelist fields and
dropped it, so no client consumer ever saw it. Project model and
manufacturer (manufacturer disambiguates bare model strings like "3950")
at both boundaries, and add a test that drives the real middleware and
browser catalog end to end.

server/providers/cctv.js

@@ -162,6 +162,8 @@ export function cctvProxy({ sourceRoot = process.cwd() } = {}) {
               sourceKind:
                 source.sourceKind || (source.url ? 'configured' : 'fallback'),
               poseSource: source.poseSource,
+              model: source.model || '',
+              manufacturer: source.manufacturer || '',
               license: source.license,
               credit: source.credit || '',
               code: source.code || '',