refactor: Update player seek functionality to use consistent position field across schemas and services

tests/services/test_player.py

@@ -65,14 +65,13 @@ class TestPlayerState:
         assert result["status"] == "playing"
         assert result["mode"] == "loop"
         assert result["volume"] == 75
-        assert result["current_sound_id"] == 1
-        assert result["current_sound_index"] == 0
-        assert result["current_sound_position"] == 5000
-        assert result["current_sound_duration"] == 30000
-        assert result["playlist_id"] == 1
-        assert result["playlist_name"] == "Test Playlist"
-        assert result["playlist_length"] == 5
-        assert result["playlist_duration"] == 150000
+        assert result["position"] == 5000
+        assert result["duration"] == 30000
+        assert result["index"] == 0
+        assert result["playlist"]["id"] == 1
+        assert result["playlist"]["name"] == "Test Playlist"
+        assert result["playlist"]["length"] == 5
+        assert result["playlist"]["duration"] == 150000
 
     def test_serialize_sound_with_sound_object(self):
         """Test serializing a sound object."""