Add multi-station support, GWR fares API, and Circle line improvements

- Support any station with direct trains to Paddington; station CRS code
  is now part of the URL (/results/<crs>/<slug>/<date>)
- Load station list from data/direct_to_paddington.tsv; show dropdown on
  index page; 404 for unknown station codes
- Fetch live GWR walk-on fares via api.gwr.com for all stations (SSS/SVS/SDS
  with restrictions already applied per train); cache 30 days
- Scrape Paddington arrival platform numbers from RTT
- Show unreachable morning Eurostars (before first reachable service only)
- Circle line: show actual KX St Pancras arrival times (not check-in estimate)
  and add a second backup service in the transfer column
- Widen page max-width to 1100px for longer station names

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

templates/base.html

@@ -43,7 +43,7 @@
     }
 
     main {
-      max-width: 960px;
+      max-width: 1100px;
       margin: 2rem auto;
       padding: 0 1rem;
     }