Run ruff format changes and finalize indentation and lint fixes.

tests/test_theme_manager.py

@@ -7,10 +7,7 @@ import unittest
 from unittest.mock import Mock, patch
 import tkinter as tk
 
-# Add src to path for imports
-sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..', 'src'))
-
-from theme_manager import ThemeManager
+from thechart.ui import ThemeManager
 
 
 class TestThemeManagerMenu(unittest.TestCase):