feat(game-detail): link sections to filtered lists (#66)

Add "View all" links to the Purchases / Sessions / Play Events sections
on the game-detail page, each pointing at the matching filtered list view
via filter_url(). Pure consumer of the #56 filter_url()/where() helpers;
no new filter machinery.

- _game_section() gains an optional view_all_url, rendered as a gray xs
  button beside the heading (shown only when the section is non-empty).
- New arrowright icon for the link.
- Tests: each section renders the expected escaped href; a parity test
  asserts each link's filter scopes to the game and excludes others.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_game_detail_links.py

@@ -0,0 +1,87 @@
+"""Rendering tests: game-detail sections wire "View all" links to filtered lists (#66)."""
+
+from datetime import datetime, timezone
+
+import pytest
+from django.utils.html import escape
+
+from games.filters import (
+    PlayEventFilter,
+    PurchaseFilter,
+    SessionFilter,
+    filter_url,
+)
+from games.models import Game, Platform, PlayEvent, Purchase, Session
+from games.views.game import view_game
+
+
+def _dt(day, hour=12):
+    return datetime(2024, 6, day, hour, 0, tzinfo=timezone.utc)
+
+
+@pytest.fixture
+def game(db):
+    platform = Platform.objects.create(name="PC")
+    game = Game.objects.create(
+        name="Test Game", platform=platform, status=Game.Status.PLAYED
+    )
+    Session.objects.create(game=game, timestamp_start=_dt(1), timestamp_end=_dt(1, 13))
+    Purchase.objects.create(date_purchased=_dt(1), type=Purchase.GAME).games.set([game])
+    PlayEvent.objects.create(game=game, ended=_dt(2))
+    return game
+
+
+@pytest.fixture
+def rendered(game, rf, django_user_model):
+    user = django_user_model.objects.create_user(username="u", password="p")
+    request = rf.get(f"/game/{game.id}/")
+    request.user = user
+    request.session = {}
+    return view_game(request, game.id).content.decode()
+
+
+def test_sessions_section_links_to_filtered_sessions(game, rendered):
+    href = escape(filter_url(SessionFilter.where(game=[game.id])))
+    assert href in rendered
+
+
+def test_purchases_section_links_to_filtered_purchases(game, rendered):
+    href = escape(filter_url(PurchaseFilter.where(games=[game.id])))
+    assert href in rendered
+
+
+def test_playevents_section_links_to_filtered_playevents(game, rendered):
+    href = escape(filter_url(PlayEventFilter.where(game=[game.id])))
+    assert href in rendered
+
+
+def test_link_filters_scope_to_game(game):
+    """Each link's filter selects exactly the game's own records, not another
+    game's (parity between the section and the filtered list it links to)."""
+    other = Game.objects.create(name="Other", platform=game.platform)
+    Session.objects.create(game=other, timestamp_start=_dt(3), timestamp_end=_dt(3, 13))
+    Purchase.objects.create(date_purchased=_dt(3), type=Purchase.GAME).games.set(
+        [other]
+    )
+    PlayEvent.objects.create(game=other, ended=_dt(4))
+
+    sessions = Session.objects.filter(SessionFilter.where(game=[game.id]).to_q())
+    assert list(sessions) == list(game.sessions.all())
+
+    purchases = Purchase.objects.filter(PurchaseFilter.where(games=[game.id]).to_q())
+    assert list(purchases) == list(game.purchases.all())
+
+    playevents = PlayEvent.objects.filter(PlayEventFilter.where(game=[game.id]).to_q())
+    assert list(playevents) == list(game.playevents.all())
+
+
+def test_no_view_all_for_empty_section(db, django_user_model, rf):
+    """A game with no sessions/purchases/playevents shows no 'View all' link."""
+    platform = Platform.objects.create(name="PC")
+    empty_game = Game.objects.create(name="Empty", platform=platform)
+    user = django_user_model.objects.create_user(username="u2", password="p")
+    request = rf.get(f"/game/{empty_game.id}/")
+    request.user = user
+    request.session = {}
+    html = view_game(request, empty_game.id).content.decode()
+    assert "View all" not in html