implement basic player_detail_view.dart

test/db_tests/aggregates/group_test.dart

@@ -194,6 +194,31 @@ void main() {
         expect(allGroups, isEmpty);
       });
 
+      test('getGroupsByPlayer() works correctly', () async {
+        await database.groupDao.addGroupsAsList(
+          groups: [testGroup1, testGroup2],
+        );
+
+        final groups = await database.groupDao.getGroupsByPlayer(
+          playerId: testPlayer2.id,
+        );
+
+        expect(groups, hasLength(2));
+        expect(groups.any((group) => group.id == testGroup1.id), isTrue);
+        expect(groups.any((group) => group.id == testGroup2.id), isTrue);
+      });
+
+      test(
+        'getGroupsByPlayer() returns empty list for non-existent player',
+        () async {
+          final groups = await database.groupDao.getGroupsByPlayer(
+            playerId: 'non-existent-player-id',
+          );
+
+          expect(groups, isEmpty);
+        },
+      );
+
       test('addGroupsAsList() with duplicate groups only adds once', () async {
         await database.groupDao.addGroupsAsList(
           groups: [testGroup1, testGroup1, testGroup1],