Fix import errors: json in character_service, QPixmap in installed_tab

Author: Spieler1ONE1

src/core/character_service.py

@@ -1,6 +1,7 @@
 import logging
 import shutil
 import zipfile
+import json
 from datetime import datetime
 from pathlib import Path
 from typing import List, Tuple, Optional

src/ui/tabs/installed_tab.py

@@ -8,7 +8,7 @@
 from src.ui.widgets import CharacterCard
 from src.ui.anim_config import AnimConfig
 import os
-from PySide6.QtGui import QDesktopServices
+from PySide6.QtGui import QDesktopServices, QPixmap
 from PySide6.QtCore import QUrl, QTimer
 from src.ui.widgets.skeleton import SkeletonCard