Consider re-implementation based on Textual

[chentoast]

Building on an actual TUI framework like textual could make for a better user experience and more features like:

• Mouse support
• Cleaner handling of user input and keypresses
• Cleaner scrolling logic (the current implementation of scrolling is hacky and slow)

Using textual seems like the best option, since it interfaces well with Rich. Some blockers need to be addressed before this happens though:

• [ ] A user input widget for Textual
• [ ] Current Textual bug with rendering Padding renderables
• [ ] A separate system for image scrolling