trip: redesign itinerary display and add trip list macro

- Add render_trip_element macro to macros.html; use it in trip_item for
  the trip list page, giving a consistent one-line-per-element format
  with emoji, route, times, duration, operator, distance, and CO₂
- Redesign trip_page.html itinerary: day headers use date-only (no year),
  condense check-out to a single accent line, show time-only on transport
  cards, humanise duration (Xh Ym), km-only distance, add CO₂ for all
  transport modes, fix seat display for integer seat values
- Fix UndefinedError on /trip/past caused by absent 'arrive' key (Jinja2
  Undefined is truthy) and date-only depart/arrive fields (no .date())
- Improve mobile map layout: text column before map in HTML order, reduce
  mobile map heights, hide toggle button on mobile
- Add trips.css with design system (Playfair Display / Source Sans 3 /
  JetBrains Mono, navy/gold/amber palette, card variants by type)
- Add tests/test_trip_list_render.py covering the rendering edge cases

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

tests/test_trip_list_render.py

@@ -0,0 +1,188 @@
+"""Tests for trip list template rendering.
+
+Covers edge cases found in real data that caused UndefinedError / AttributeError:
+  1. Flight where 'arrive' key is entirely absent (older data format).
+     Jinja2 returns Undefined for missing dict keys, which is truthy, so a
+     plain truthiness check on item.arrive would pass and then .date() would
+     raise UndefinedError.
+  2. Train where depart/arrive are date objects (not datetime).
+     datetime.date has no .date() method, so item.depart.date() raises
+     AttributeError (surfaced as UndefinedError inside Jinja2).
+"""
+
+from datetime import date, datetime, timezone
+
+import flask
+import pytest
+
+import web_view
+from agenda.types import TripElement
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+
+class _FakeTrip:
+    """Minimal trip stub sufficient for render_trip_element."""
+
+    show_flags = False
+
+
+def _render(element: TripElement) -> str:
+    """Render a single TripElement via the render_trip_element macro."""
+    with web_view.app.app_context():
+        with web_view.app.test_request_context():
+            flask.g.user = web_view.User(is_authenticated=False)
+            macros = web_view.app.jinja_env.get_template("macros.html")
+            return macros.module.render_trip_element(element, _FakeTrip())
+
+
+def _flight(detail: dict) -> TripElement:
+    return TripElement(
+        start_time=detail["depart"],
+        title="test flight",
+        element_type="flight",
+        detail=detail,
+        start_loc="Origin",
+        end_loc="Dest",
+    )
+
+
+def _train(detail: dict) -> TripElement:
+    return TripElement(
+        start_time=detail["depart"],
+        title="test train",
+        element_type="train",
+        detail=detail,
+        start_loc=detail["from"],
+        end_loc=detail["to"],
+    )
+
+
+# ---------------------------------------------------------------------------
+# Unit tests — specific edge cases
+# ---------------------------------------------------------------------------
+
+
+def test_flight_missing_arrive_key() -> None:
+    """Flight with no 'arrive' key must not raise UndefinedError.
+
+    Older trips store flights without an arrival time.  Jinja2 returns
+    Undefined (truthy!) for absent dict keys, so a bare truthiness check
+    was insufficient — only 'is defined' correctly guards against it.
+    """
+    element = _flight(
+        {
+            "depart": datetime(2023, 7, 1, 13, 20, tzinfo=timezone.utc),
+            # 'arrive' key intentionally absent
+            "from": "TIA",
+            "to": "LHR",
+            "flight_number": "BA123",
+            "airline_code": "BA",
+            "airline_name": "British Airways",
+            "distance": 2000.0,
+        }
+    )
+    result = _render(element)
+    assert "Origin" in result
+    assert "Dest" in result
+    assert "13:05" not in result  # arrive time should not appear
+
+
+def test_flight_arrive_is_none() -> None:
+    """Flight where 'arrive' key exists but value is None must render cleanly."""
+    element = _flight(
+        {
+            "depart": datetime(2023, 7, 1, 13, 20, tzinfo=timezone.utc),
+            "arrive": None,
+            "from": "TIA",
+            "to": "LHR",
+            "flight_number": "BA123",
+            "airline_code": "BA",
+            "airline_name": "British Airways",
+            "distance": 2000.0,
+        }
+    )
+    result = _render(element)
+    assert "Origin" in result
+
+
+def test_train_date_only_fields() -> None:
+    """Train with date (not datetime) depart/arrive must not raise AttributeError.
+
+    Some older train entries record only the travel date with no time.
+    datetime.date has no .date() method, so item.depart.date() would fail.
+    """
+    element = _train(
+        {
+            "depart": date(2024, 10, 22),
+            "arrive": date(2024, 10, 22),
+            "from": "Llandrindod",
+            "to": "Llandovery",
+            "operator": "Transport for Wales",
+        }
+    )
+    result = _render(element)
+    assert "Llandrindod" in result
+    assert "Llandovery" in result
+
+
+def test_train_overnight_datetime() -> None:
+    """Overnight train (arrive on next day) shows night moon emoji and +1 day."""
+    tz = timezone.utc
+    element = _train(
+        {
+            "depart": datetime(2026, 1, 19, 19, 6, tzinfo=tz),
+            "arrive": datetime(2026, 1, 20, 10, 13, tzinfo=tz),
+            "from": "Brussels Midi",
+            "to": "Vienna Hbf",
+            "operator": "ÖBB",
+        }
+    )
+    result = _render(element)
+    assert "🌙" in result
+    assert "+1 day" in result
+
+
+def test_train_seat_as_integer() -> None:
+    """Train with seat as an integer (not a list) must render without error."""
+    tz = timezone.utc
+    element = _train(
+        {
+            "depart": datetime(2025, 5, 26, 13, 5, tzinfo=tz),
+            "arrive": datetime(2025, 5, 26, 13, 29, tzinfo=tz),
+            "from": "Wánchaq",
+            "to": "Puno",
+            "coach": "C",
+            "seat": 1,
+        }
+    )
+    result = _render(element)
+    assert "Wánchaq" in result
+
+
+# ---------------------------------------------------------------------------
+# Integration tests — render the real trip list pages end-to-end
+# ---------------------------------------------------------------------------
+
+
+@pytest.fixture
+def client():
+    """Flask test client."""
+    web_view.app.config["TESTING"] = True
+    with web_view.app.test_client() as c:
+        yield c
+
+
+def test_past_trips_page_renders(client) -> None:
+    """Past trips list page renders without any template errors (HTTP 200)."""
+    response = client.get("/trip/past")
+    assert response.status_code == 200
+
+
+def test_future_trips_page_renders(client) -> None:
+    """Future trips list page renders without any template errors (HTTP 200)."""
+    response = client.get("/trip/future")
+    assert response.status_code == 200