Make alt text mandatory

[diesocke]

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

Blind or visually impaired people are dependant on alt texts to understand images. Bluesky has a function to let the user be reminded of missing alt texts. However, one has to become aware of the problem that visually impaired people cannot interpret images without alt texts.

Describe the solution you'd like
Reverse the default setting of "Require alt text before posting" to set.

Describe alternatives you've considered
There are numerous people commenting skeets lacking alt text with hints to set this preference manually. As people often are unaware that the are excluding visually impaired people this leads to missunderstanding and conflict.

Additional context

[t0b1hh]

Yep. Default should be inverted.

But a user should still be able to disable the requiredment of alt text.

There are also people who are not able to describe images. They should still be able to post images even w/o alt text.