Add Astra child theme for Hop On Hop Off header & footer

- disables Astra header/footer via astra_header/astra_footer hooks and renders
  custom design markup (logo, nav dropdown, footer columns, socials, support)
- chrome.css scoped to .hoho (generated from the design source); chrome.js for
  burger/submenu/sticky/back-to-top; bundled icon sprite (reuses plugin's)
- parameterize scope-css.js scope via VC_SCOPE env

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01J4hNL1PSHxXbu94SCenpKj

viator-collector/build/scope-css.js

@@ -17,7 +17,7 @@
 'use strict';
 const fs = require('fs');
 
-const SCOPE = '.vc-app';
+const SCOPE = process.env.VC_SCOPE || '.vc-app';
 
 function prefixSelector(sel) {
   sel = sel.trim();