Show Eurostar Standard prices and total journey cost on results page

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>

app.py

@@ -8,6 +8,7 @@ from cache import get_cached, set_cached
 import scraper.eurostar as eurostar_scraper
 import scraper.realtime_trains as rtt_scraper
 from trip_planner import combine_trips, find_unreachable_morning_eurostars
+from scraper.eurostar import fetch_prices as fetch_eurostar_prices
 
 RTT_PADDINGTON_URL = (
     "https://www.realtimetrains.co.uk/search/detailed/"
@@ -80,10 +81,12 @@ def results(slug, travel_date):
 
     rtt_cache_key = f"rtt_{travel_date}"
     es_cache_key = f"eurostar_{travel_date}_{destination}"
+    prices_cache_key = f"eurostar_prices_{travel_date}_{destination}"
 
     cached_rtt = get_cached(rtt_cache_key)
     cached_es = get_cached(es_cache_key)
-    from_cache = bool(cached_rtt and cached_es)
+    cached_prices = get_cached(prices_cache_key)
+    from_cache = bool(cached_rtt and cached_es and cached_prices)
 
     error = None
 
@@ -108,7 +111,28 @@ def results(slug, travel_date):
             msg = f"Could not fetch Eurostar times: {e}"
             error = f"{error}; {msg}" if error else msg
 
+    if cached_prices:
+        eurostar_prices = cached_prices
+    else:
+        try:
+            eurostar_prices = fetch_eurostar_prices(destination, travel_date)
+            set_cached(prices_cache_key, eurostar_prices)
+        except Exception as e:
+            eurostar_prices = {}
+            msg = f"Could not fetch Eurostar prices: {e}"
+            error = f"{error}; {msg}" if error else msg
+
     trips = combine_trips(gwr_trains, eurostar_trains, travel_date, min_connection, max_connection)
+
+    # Annotate each trip with Eurostar Standard price and total cost
+    for trip in trips:
+        es_price = eurostar_prices.get(trip['depart_st_pancras'])
+        trip['eurostar_price'] = es_price
+        if es_price is not None:
+            trip['total_price'] = trip['ticket_price'] + es_price
+        else:
+            trip['total_price'] = None
+
     unreachable_morning_services = find_unreachable_morning_eurostars(
         gwr_trains,
         eurostar_trains,
@@ -116,6 +140,9 @@ def results(slug, travel_date):
         min_connection,
         max_connection,
     )
+    for svc in unreachable_morning_services:
+        svc['eurostar_price'] = eurostar_prices.get(svc['depart_st_pancras'])
+
     result_rows = sorted(
         [{'row_type': 'trip', **trip} for trip in trips]
         + [{'row_type': 'unreachable', **service} for service in unreachable_morning_services],