feat(cctv): add Houston TranStar camera pack

Register the keyless TranStar snapshot catalog as a live CCTV source,
synthesize frame URLs from validated numeric camera ids, and keep the
nearest cameras to Houston's metro cores under the existing catalog ceiling.

server/providers/cctv/catalog.js

@@ -25,6 +25,7 @@ import {
   loadVegvesenSourcesFromOpenData,
   loadNycSourcesFromOpenData,
   loadTorontoSourcesFromOpenData,
+  loadHoustonSourcesFromOpenData,
 } from './sources.js';
 
 /** Env kill switch: unset or anything but "0" means enabled. */
@@ -144,6 +145,11 @@ const LIVE_PACKS = [
     enabled: () => envOptIn('CCTV_LITHUANIA_ENABLED'),
     load: loadLithuaniaSources,
   },
+  {
+    name: 'houston',
+    enabled: () => envEnabled('CCTV_HOUSTON_ENABLED'),
+    load: loadHoustonSourcesFromOpenData,
+  },
 ];
 /**
  * Load CCTV sources from a local JSON file (CCTV_SOURCES_FILE env or default).