* Embed a tweet by URL
* Clean up imports
* Prevent tweetId from getting interpreted as a number
* Use a single place to embed iframe, Youtube, and Tweets
* Support Manifold and Metaculus embeds
* Remove unused import
* Simplify Manifold paste logic
* Clean up embed rewrite code
* Add back comment
* Rejigger config so tsx is only in web/
* Clean up comment
* Revert unnecessary tsconfig change
* Fix placeholder
* Lighten placeholder
