Drive-by: browser/server.py was never linted (pre-commit ruff is scoped to
backend/), so #909 left an unused noqa + a 101-char line. Cleaned up while
editing this file for the proxy fix.
Prod smoke: tradein-browser fetched avito but got the ~400KB soft-block stub
(preloadedState present but priceDetailed=0, firewall=0) — because camoufox ran
with NO proxy (datacenter IP). Root cause: server.py read SCRAPER_PROXY_URL, but
the proxy in backend/.env.runtime is named AVITO_PROXY_URL (mobileproxy, #623) —
the same var curl_cffi-avito uses. So the var was empty in the browser container.
Fix: read AVITO_PROXY_URL first, SCRAPER_PROXY_URL as a generic fallback. One-line
env-name swap; the value is the working mobileproxy egress already on the host.
After deploy, re-run tradein-mvp/scripts/browser-smoke.sh — expect real data
(priceDetailed>0, ~1.4MB, firewall 0). IP rotation (AVITO_PROXY_ROTATE_URL) stays
backend-side and keeps working (same proxy endpoint, changing egress IP).
Refs #905, #883, #623
