## What kind of change does this PR introduce?
Chore
## What is the current behavior?
Sign-in testimonials are drawn from the weighted tweet pool in
`packages/shared-data/tweets.ts`. shadcn's quote is not included.
Resolves
[FE-3978](https://linear.app/supabase/issue/FE-3978/add-shadcn-tweet-to-sign-in-page).
## What is the new behavior?
Adds [@shadcn](https://x.com/shadcn/status/1672913636132790272)'s tweet
("Supabase is really good. ⚡") with weight `10`, plus the profile image
under `twitter-profiles`.
## Additional context
Weighted selection on the Studio sign-in page and `topTweets` on www
both pick this up from the shared list.
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Documentation**
* Updated tweet module documentation to explain how tweet `weight`
impacts Studio sign-in weighted random selection and the `topTweets`
list (top 18 by weight).
* **New Content**
* Added a new tweet to the collection with an explicit `weight` of 10,
making it eligible for weighted selection and top-ranked inclusion.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
* add new tweets and remove old
* randomise on sign in
* prefer higher weights
* single source of truth
* additional tweet
* clean up extraneous content
Danny White