feat: Enhance Python environment setup with system Python option and improve dependency installation

refactor: Clean up imports in currencies and users routes
fix: Update theme settings saving logic and clean up test imports

tests/unit/test_theme_settings.py

@@ -1,15 +1,8 @@
-import pytest
 from sqlalchemy.orm import Session
-from fastapi.testclient import TestClient
 
-from main import app
-from models.theme_setting import ThemeSetting
 from services.settings import save_theme_settings, get_theme_settings
 
 
-client = TestClient(app)
-
-
 def test_save_theme_settings(db_session: Session):
     theme_data = {
         "theme_name": "dark",