Normalize email input by stripping whitespace and converting to lowercase in login endpoint, remove EmailStr validation in favor of plain string type, move dark mode class toggle from Layout to App component for better initialization, add theme toggle button to login page, and set dark mode as default theme when no preference is stored
Add TypeScript declarations for Vite environment variables including VITE_API_BASE_URL to enable type-safe access to import.meta.env in the frontend application