## Summary
This PR adds a playground for Red Knot
[Screencast from 2024-08-14
10-33-54.webm](https://github.com/user-attachments/assets/ae81d85f-74a3-4ba6-bb61-4a871b622f05)
Sharing does work 😆 I just forgot to start wrangler.
It supports:
* Multiple files
* Showing the AST
* Showing the tokens
* Sharing
* Persistence to local storage
Future extensions:
* Configuration support: The `pyproject.toml` would *just* be another
file.
* Showing type information on hover
## Blockers
~~Salsa uses `catch_unwind` to break cycles, which Red Knot uses
extensively when inferring types in the standard library.
However, WASM (at least `wasm32-unknown-unknown`) doesn't support
`catch_unwind` today, so the playground always crashes when the type
inference encounters a cycle.~~
~~I created a discussion in the [salsa
zulip](https://salsa.zulipchat.com/#narrow/stream/333573-salsa-3.2E0/topic/WASM.20support)
to see if it would be possible to **not** use catch unwind to break
cycles.~~
~~[Rust tracking issue for WASM catch unwind
support](https://github.com/rust-lang/rust/issues/118168)~~
~~I tried to build the WASM with the nightly compiler option but ran
into problems because wasm-bindgen doesn't support WASM-exceptions. We
could try to write the binding code by hand.~~
~~Another alternative is to use `wasm32-unknown-emscripten` but it's
rather painful to build~~
## Summary
This is prep-work for the Red Knot playground. We'll have two
playgrounds, one for Red Knot and Ruff.
I want to share some components between the two, a "shared" NPM package
in a local workspace is a great fit for that.
I also want to share the dev dependencies and dev scripts. Again, NPM
workspaces are great for that.
This PR also sets up a CI workflow for the playground to prevent
surprises during the release.
## Test Plan
CI, local `npm install`, `npm start`, ...
I verified that the new CI step fails if there's a typescript or
formatting error.
* [Deployment test
run](3890552435)
