Hook the production deploy (deploy/deploy.sh) to ping IndexNow after the health
check passes, so new/changed pages reach Bing/DuckDuckGo/Yandex without a manual
run. Best-effort — wrapped so it can never fail a deploy — and it sources
/etc/thermograph.env so its key matches the one the running service serves.
To avoid re-blasting ~14k URLs on every code push, indexnow.py gains a
--if-changed mode gated by a signature of the URL set (persisted to
data/indexnow_state.txt): code-only deploys skip; a deploy that adds or removes a
city submits. `make indexnow` still forces a full submit.
The population-ranked global top-500 skewed to Asian megacities and missed
high-English-search-demand cities. gen_cities.py now tops up with the top ~250
cities from English-speaking countries (US/GB/CA/AU/NZ/IE/ZA) not already in the
global set, so US coverage goes 13->146, GB 2->42, CA 3->29, etc. (Seattle, Boston,
Manchester, Melbourne, Auckland, Dublin, ...). cities.json regenerated to 750.
Both deploy scripts now launch warm_cities.py automatically after the health check,
detached (dev: a systemd --user transient unit; prod: setsid/nohup), so the city
pages serve from cache without a manual step; idempotent, so only the first deploy
does the full warm. DEPLOY.md updated.
