Fetches prices via the site-api.eurostar.com GraphQL gateway
(NewBookingSearch operation, discovered with Playwright). Adds
fetch_prices() to scraper/eurostar.py using requests, caches results,
annotates each trip with eurostar_price and total_price, and shows an
ES Std column plus total cost (duration + price) in the results table.
The Transfer column is hidden on small screens for mobile usability.
Closes#4
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
