SEO: add 250 English-market city pages; auto-warm archives on deploy (#97)

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.

deploy/deploy.sh

@@ -9,6 +9,17 @@ APP_DIR="${APP_DIR:-/opt/thermograph}"
 BRANCH="${BRANCH:-main}"
 cd "$APP_DIR"
 
+# Pre-warm the ~750 city-page archives so /climate pages serve from cache and a
+# search-engine crawl never bursts the archive API quota. Detached + backgrounded
+# so it never blocks the deploy or health check; idempotent (skips already-cached
+# cells), so it's cheap on every deploy after the first full warm.
+warm_city_archives() {
+  mkdir -p "$APP_DIR/logs"
+  echo "==> Warming city-page archives in the background (logs/warm-cities.log)"
+  setsid nohup bash -c "cd '$APP_DIR/backend' && exec '$APP_DIR/.venv/bin/python' warm_cities.py --pace 2" \
+    </dev/null >"$APP_DIR/logs/warm-cities.log" 2>&1 &
+}
+
 echo "==> Fetching $BRANCH"
 git fetch --prune origin "$BRANCH"
 git reset --hard "origin/$BRANCH"
@@ -31,6 +42,7 @@ url="http://127.0.0.1:${PORT}${BASE%/}/"
 for i in $(seq 1 15); do
   if curl -fsS -o /dev/null "$url"; then
     echo "==> OK: $url is serving"
+    warm_city_archives
     exit 0
   fi
   sleep 1