Simplify theme toggle to dark/light only

- Remove system theme option
- Refactor ModeToggle component for immediate theme switching
- Implement local state management for smoother transitions
- Persist theme preference in localStorage
- Update icon display logic for better visual feedback

This commit addresses the issue of delayed theme switching and
simplifies the user experience by offering only dark and light modes.

package.json

@@ -51,6 +51,7 @@
     "styled-components": "^6.1.12",
     "tailwind-merge": "^2.5.1",
     "tailwindcss-animate": "^1.0.7",
+    "zen-website": "file:",
     "zod": "^3.23.8"
   },
   "devDependencies": {