A proxy in a different country paired with the host timezone is the
classic timezone_mismatch signal, so a session with a proxy and no
explicit timezone now resolves the zone automatically.
- discover the egress IP through the proxy (SOCKS via requests[socks]),
map it to an IANA zone with an offline mmdb (daijro/geoip-all-in-one,
downloaded + cached like the Firefox binary; GPL so not vendored)
- precedence: explicit zone wins; ""+proxy and "auto"+proxy resolve;
""/"auto" without a proxy stay host; "host"/"local" force host TZ
- fail-early when a proxy is set but the zone cannot be resolved, never
a silent host-TZ fallback
- deps: requests[socks], maxminddb, tzdata (zoneinfo ships no DB on Windows)
- resolve_session_timezone / ensure_geoip_mmdb exported for integrations