Fix stops filter hiding options after selection

Add booking options page with cabin-aware fare tiers

Add round-trip date validation and 12-month booking window

Fix auth cookie not sent in HF Spaces iframe context

Fix auth token invalidated on server restart

Add flight booking flow with payment validation

Track airline_routes.json with Git LFS

Add HF Spaces deployment config and passkey auth

Add Google Flights-style step-based round-trip booking flow

Fix local-time display bug, add Asia departure patterns, popularity extension

Add realistic departure time distributions by route type

Add flight amenities: legroom, WiFi, power/USB, video per segment

Add Google Flights-style "Best/Other" sections, emissions, rich detail view

Fix time+1 wrapping, add airline discount pricing, document fare engine

Fix 500 error on routes with empty carriers, align flight results grid

Add flight booking website (Google Flights clone)