chore: scaffold monorepo

[sripwoud]

Towards replacing the template rendering engine used for the web interface by a JS/TS application.
In the internal PSE #dogfood, it seems we were all in favor on using a monorepo to manage the freedit rs backend and the to be developed JS client.

I picked a few tools that I am setting up in this PR:

• bun as JS runtime and node package manager

• just as tasks runner

• vite: JS/TS front end build tool

• tanstack router: client side router
  Right now I am just "dangerously setting" the inner html in one route of client app from what the server gives. But of course we should not keep doing that way, this is just for demo/test purposes atm. Indeed atm the server only serves html documents (the rinja template rendering engine). Eventually we want to have a server that gives us JSON and fetch that client side, and let react build the html docs (see server: implement json api layer #5 and server: remove template rendering logic and deps #6).

  

Test plan

• Spin up the server and client: eg with just dev
• you should not see any errors or warnings
• go to localhost:5173 . Click on the inn link. You should see the same content as on localhost:3001 (but displayed very ugly)

[adria0]

Not checked JS stuff because I do not have expertice on this, but overall, LGTM.

[jacque006]

JS setup looks good to me 👍

I assume based on these changes that we will no longer be pulling from freedit upstream. Still might be doable to as custom patches if they make smaller updates. As an example of something we might want: freedit-org#306

[jacque006]

We'll need to port this to https://github.com/privacy-scaling-explorations/pse-forums , can likely just push main there. Will also include db snapshot logic from #1 & #2

[sripwoud]

@jacque006 yes i wanted to merge it here first as you had started to review it here.
I ll push to main on pse-forums