ref(lint): ban React.Fragment in favor of named Fragment import

[natemoo-re]

Adds no-restricted-syntax rules banning both React.Fragment and <React.Fragment> — enforces import {Fragment} from 'react' instead. Same pattern as the existing React.forwardRef ban.

Fragment was already used in 936 files vs 23 files that used React.Fragment. These have been updated. Left snapshot strings and lint rule test fixtures alone.

Unfortunately not autofixable via no-restricted-syntax, but agents should take care of these automatically most of the time.

[github-actions]

📊 Type Coverage Diff

✅ No new type safety issues introduced. Coverage: 93.57%

[JoshuaKGoldberg]

💯 yessss I was hoping to eventually bring up standardizing!

https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-fragments.md might be a good place to look that already does this with auto-fixing? If it doesn't have exactly what we prefer, maybe a good OSS contribution?

Edit: I mean, I don't think that rule has this style, but maybe there's a contribution opportunity to add that there, or to a separate stylistic rule?

[natemoo-re]

@JoshuaKGoldberg that's a good point, we already use it to enforce the longhand! There's a help wanted issue so that would likely be accepted. In the middle of a bunch of stuff, but if I get any time I'll try to circle back.