Tag names need validation

[andypiper]

Postmarks happily allowed me to type a tag name of "developer relations" with a space, showed #developer relations in the UI, but then reported an error about the format of the tag when I hit save. It would be better to validate and/or force the entry of compliant tag names.

[ckolderup]

thanks Andy!

[andypiper]

I’d also suggest normalisation (potentially to lowercase).

[ckolderup]

I think we want to allow mixed-case, I've heard it's an accessibility issue (it's come up a few times on Mastodon, but this source seems to cover the main points I've seen discussed: https://www.boia.org/blog/make-your-hashtags-accessible)