Show alt text for an image as a tooltip

[surfdude29]

Is your feature request related to a problem? Please describe.

When using Bluesky on the web, if you see an image that has alt text and would like to know what it says it can be annoying to have to open the image to read the alt text.

Describe the solution you'd like

Ideally, the alt text for an image would be displayed as a tooltip when you hover your mouse over either (1) any part of the image or (2) just the ALT indicator (and maybe a larger target region around it as it's quite small now.)

I'm unsure which solution would work best for the most users (I can imagine some users getting annoyed if the first solution were implemented and they have no interest in seeing the alt text.)

Describe alternatives you've considered

The alternative is to keep the current behaviour where you need to open an image to view its alt text.

Additional context

This was inspired by posts from two users:

https://bsky.app/profile/ygalanter.bsky.social/post/3ktilxmolvb2b
https://bsky.app/profile/botvolution.bsky.social/post/3ktikzwecxq2q