Tidy results table layout and centralise connection defaults

- Redesign results table from 8 columns to 4 (National Rail, Transfer,
  Eurostar, Total), making GWR and Eurostar legs consistent with each other
- Move CET label next to Paris arrival time; show duration · train number
  on one line below
- Move "Too early" label into the National Rail column for unreachable rows
- Remove horizontal scrollbar (drop card-scroll / overflow-x: auto)
- Add DEFAULT_MIN_CONNECTION / DEFAULT_MAX_CONNECTION to config/default.py
  (70 / 150 min); remove all hardcoded fallback values from app.py and
  templates
- Redirect to clean URL when both connection params equal their defaults;
  omit params from all generated links when at default values

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

app.py

@@ -65,11 +65,14 @@ DESTINATIONS = {
 @app.route("/")
 def index():
     today = date.today().isoformat()
+    default_min, default_max = _get_defaults()
     return render_template(
         "index.html",
         destinations=DESTINATIONS,
         today=today,
         stations=STATIONS,
+        default_min_connection=default_min,
+        default_max_connection=default_max,
         valid_min_connections=sorted(VALID_MIN_CONNECTIONS),
         valid_max_connections=sorted(VALID_MAX_CONNECTIONS),
     )
@@ -79,6 +82,21 @@ VALID_MIN_CONNECTIONS = {45, 50, 60, 70, 80, 90, 100, 110, 120}
 VALID_MAX_CONNECTIONS = {60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180}
 
 
+def _get_defaults():
+    return (
+        app.config["DEFAULT_MIN_CONNECTION"],
+        app.config["DEFAULT_MAX_CONNECTION"],
+    )
+
+
+def _parse_connection(raw, default, valid_set):
+    try:
+        val = int(raw)
+    except (TypeError, ValueError):
+        return default
+    return val if val in valid_set else default
+
+
 @app.route("/search")
 def search():
     slug = request.args.get("destination", "")
@@ -86,18 +104,13 @@ def search():
     station_crs = request.args.get("station_crs", "BRI")
     if station_crs not in STATION_BY_CRS:
         station_crs = "BRI"
-    try:
-        min_conn = int(request.args.get("min_connection", 50))
-    except ValueError:
-        min_conn = 50
-    if min_conn not in VALID_MIN_CONNECTIONS:
-        min_conn = 50
-    try:
-        max_conn = int(request.args.get("max_connection", 110))
-    except ValueError:
-        max_conn = 110
-    if max_conn not in VALID_MAX_CONNECTIONS:
-        max_conn = 110
+    default_min, default_max = _get_defaults()
+    min_conn = _parse_connection(
+        request.args.get("min_connection"), default_min, VALID_MIN_CONNECTIONS
+    )
+    max_conn = _parse_connection(
+        request.args.get("max_connection"), default_max, VALID_MAX_CONNECTIONS
+    )
     if slug in DESTINATIONS and travel_date:
         return redirect(
             url_for(
@@ -105,8 +118,8 @@ def search():
                 station_crs=station_crs,
                 slug=slug,
                 travel_date=travel_date,
-                min_connection=min_conn,
-                max_connection=max_conn,
+                min_connection=None if min_conn == default_min else min_conn,
+                max_connection=None if max_conn == default_max else max_conn,
             )
         )
     return redirect(url_for("index"))
@@ -121,18 +134,21 @@ def results(station_crs, slug, travel_date):
     if not destination or not travel_date:
         return redirect(url_for("index"))
 
-    try:
-        min_connection = int(request.args.get("min_connection", 50))
-    except ValueError:
-        min_connection = 70
-    if min_connection not in VALID_MIN_CONNECTIONS:
-        min_connection = 70
-    try:
-        max_connection = int(request.args.get("max_connection", 110))
-    except ValueError:
-        max_connection = 150
-    if max_connection not in VALID_MAX_CONNECTIONS:
-        max_connection = 150
+    default_min, default_max = _get_defaults()
+    min_connection = _parse_connection(
+        request.args.get("min_connection"), default_min, VALID_MIN_CONNECTIONS
+    )
+    max_connection = _parse_connection(
+        request.args.get("max_connection"), default_max, VALID_MAX_CONNECTIONS
+    )
+
+    # Redirect to clean URL when both params are at their defaults
+    if (
+        "min_connection" in request.args or "max_connection" in request.args
+    ) and min_connection == default_min and max_connection == default_max:
+        return redirect(
+            url_for("results", station_crs=station_crs, slug=slug, travel_date=travel_date)
+        )
 
     user_agent = request.headers.get("User-Agent", rtt_scraper.DEFAULT_UA)
 
@@ -254,6 +270,9 @@ def results(station_crs, slug, travel_date):
     rtt_url = RTT_PADDINGTON_URL.format(crs=station_crs, date=travel_date)
     rtt_station_url = RTT_STATION_URL.format(crs=station_crs, date=travel_date)
 
+    url_min = None if min_connection == default_min else min_connection
+    url_max = None if max_connection == default_max else max_connection
+
     return render_template(
         "results.html",
         trips=trips,
@@ -278,6 +297,10 @@ def results(station_crs, slug, travel_date):
         rtt_station_url=rtt_station_url,
         min_connection=min_connection,
         max_connection=max_connection,
+        default_min_connection=default_min,
+        default_max_connection=default_max,
+        url_min_connection=url_min,
+        url_max_connection=url_max,
         valid_min_connections=sorted(VALID_MIN_CONNECTIONS),
         valid_max_connections=sorted(VALID_MAX_CONNECTIONS),
     )