Faster search-engine indexing for the ~14k climate/city/record URLs:
- IndexNow (backend/indexnow.py): instantly notify Bing/DuckDuckGo/Yandex of new
or changed URLs. Per-host key resolved env → gitignored file → generated (mirrors
push.py), served at /{key}.txt, and echoed in submissions. `submit_all()` + a
`make indexnow` CLI push every indexable URL, batched under the 10k cap. Google
doesn't use IndexNow, so it stays on the sitemap.
- Sitemap: replace the per-request today() <lastmod> (which churns every fetch and
trains crawlers to ignore lastmod) with a stable content-build date; factor the
URL list into public_paths() shared with IndexNow so the two never drift.
- Search-console verification: render google-site-verification + msvalidate.01
<meta> tags from env into every page's <head> — the SEO pages via base.html.j2
and the static pages (incl. the homepage Google verifies) via _page().
- Docs: env example documents the three new vars; .gitignore ignores the key.
Tests: key-file route, stable single-date lastmod, IndexNow payload/batching, and
verification meta on both SEO and static pages.
