feat(seo): canonicalize URLs, clean structured data, add audit gate

- Canonicals/hreflang/og point to www.bentopdf.com everywhere
- Drop fake aggregateRating; add Organization + breadcrumb JSON-LD
- Sitemap: filter 404/wasm-settings, mtime-based lastmod
- Rename locale ua → uk (correct ISO 639-1)
- Self-hoster: SITE_URL build arg, ROBOTS_NOINDEX runtime env
- Simple Mode indexable by default
- nginx: collapse .html and /index.html via 301
- SEO audit script + PR gate; runtime config noise fixed
- a11y contrast fix; language switcher gets search + scroll
- robots.txt: drop Crawl-delay

.github/workflows/static.yml

@@ -26,8 +26,9 @@ concurrency:
 # You will likely need to set BASE_URL to be the name of your repo eg 'bentopdf'
 env:
   SIMPLE_MODE: ${{ vars.SIMPLE_MODE }}
-  BASE_URL: ${{ vars.BASE_URL }}/ 
-  HUSKY: 0 
+  BASE_URL: ${{ vars.BASE_URL }}/
+  SITE_URL: ${{ vars.SITE_URL }}
+  HUSKY: 0
 
 jobs:
   # Single deploy job since we're just deploying