feat: Implement dark mode support across the application

- Added ThemeContext to manage theme state and toggle functionality.
- Updated components to support dark mode styles, including header, dashboard, and home page.
- Enhanced CSS for smooth transitions between light and dark themes.
- Modified authentication context to handle async login operations.
- Improved user experience by preserving theme preference in local storage.
- Refactored login and register pages to handle OAuth tokens and errors more gracefully.

ospabhost/frontend/.env

@@ -3,6 +3,6 @@ VITE_CARD_NUMBER="2204 2402 3323 3354"
 
 VITE_TURNSTILE_SITE_KEY=0x4AAAAAAB7306voAK0Pjx8O
 
-# API URLs (с портом 5000)
-VITE_API_URL=https://ospab.host:5000
-VITE_SOCKET_URL=wss://ospab.host:5000
+# API URLs
+VITE_API_URL=https://api.ospab.host
+VITE_SOCKET_URL=wss://api.ospab.host