feat: add infinite scrolling for memos

[liltrendi]

Overview

For users with too many notes, it feels unintuitive to keep pressing the "Load More" button. This PR aims to ease navigation by allowing the user to opt in to infinite scrolling, whereby the next posts (if any) are fetched as soon as the user reaches the bottom of the screen.

References: #4683

Changes

• Implemented infinite scrolling for memos in the home, archive, explore and profile pages
• Added a dropdown under user preferences (in settings) for users to opt in or out of this feature
• Persistence on the backend

Demo

https://github.com/user-attachments/assets/3b04f8ec-58c2-4ed5-9f3f-fc9a69c0dfa6