Feature: Add Experience/Preference Customization Options

Implement a customization menu option where users can adjust their experience preferences, such as font size and theme (dark or light mode). This feature will enhance user experience and allow for a more personalized browsing experience, hence making our platform super accessible.

**Tasks:**
- Create a customization menu UI with options for font size adjustment and theme selection.
- Implement font-size customization by setting a percentage value for `font-size` to the `html` tag on the client-side.
- Implement a theme switcher toggle for users to choose between dark and light modes (this assumes that we have already completed #14 😉)
- Save user preferences to local storage or cookies to persist settings across page reloads.

**Additional Information:**
- The customization menu should be easily accessible and intuitive for users to use.
- I got more stuff, but I can't seem to remember right now (I'll update issue description as it come)... Just share your thought if you've got any 😉

No files, tests, or entry points are named. Start by locating the existing client-side UI and the implementation for #14, then determine where the customization menu belongs; done means font-size and theme choices apply, persist across reloads, and remain accessible.

Written by the indexing model from the issue text.