Add filters to scrobble API endpoint

Add django-filter support to the ScrobbleViewSet with filters for:
- in_progress: boolean filter for active scrobbles
- visibility: enum filter (public/shared/private)
- media_type: enum filter for all 25 media types
- source: text search filter (icontains)
- played_to_completion: boolean filter
- timestamp_after/before: datetime range filters

Changes:
- Create scrobbles/api/filters.py with ScrobbleFilter class
- Add filterset_class to ScrobbleViewSet
- Filters appear in OpenAPI schema at /api/v1/scrobbles/

vrobbler/apps/scrobbles/api/filters.py

@@ -0,0 +1,29 @@
+import django_filters
+from scrobbles.constants import Visibility
+from scrobbles.models import Scrobble
+
+
+class ScrobbleFilter(django_filters.FilterSet):
+    media_type = django_filters.ChoiceFilter(choices=Scrobble.MediaType.choices)
+    visibility = django_filters.ChoiceFilter(choices=Visibility.choices)
+    in_progress = django_filters.BooleanFilter()
+    played_to_completion = django_filters.BooleanFilter()
+    source = django_filters.CharFilter(lookup_expr="icontains")
+    timestamp_after = django_filters.DateTimeFilter(
+        field_name="timestamp", lookup_expr="gte"
+    )
+    timestamp_before = django_filters.DateTimeFilter(
+        field_name="timestamp", lookup_expr="lte"
+    )
+
+    class Meta:
+        model = Scrobble
+        fields = [
+            "media_type",
+            "visibility",
+            "in_progress",
+            "played_to_completion",
+            "source",
+            "timestamp_after",
+            "timestamp_before",
+        ]

vrobbler/apps/scrobbles/api/views.py

@@ -3,6 +3,7 @@ from logging import getLogger
 from rest_framework import permissions, viewsets
 from rest_framework.decorators import action
 from rest_framework.response import Response
+from scrobbles.api.filters import ScrobbleFilter
 from scrobbles.api.serializers import (
     AudioScrobblerTSVImportSerializer,
     KoReaderImportSerializer,
@@ -23,6 +24,7 @@ class ScrobbleViewSet(viewsets.ModelViewSet):
     queryset = Scrobble.objects.all().order_by("-timestamp")
     serializer_class = ScrobbleSerializer
     permission_classes = [permissions.IsAuthenticated]
+    filterset_class = ScrobbleFilter
 
     def get_queryset(self):
         return super().get_queryset().filter(user=self.request.user)