add a self hosted example and a pwa example

so far every example is reliant on 3rd party services (partykit, clerk etc), and they don't seem to be offline-first either

this goes kinda contrary to the offline-first spirit of the project imho

what would be great to see:

a) example that works without calling 3rd parties (server should be easy with miniflare emulating workers kv and/or durable objects)
b) pwa example
c) serverside client example (node client talking to the API exposed by example A)
d) true p2p server example (communicating directly between two deployments)
e) true p2p client eg webrtc with signaling established via QR codes or via copy-paste

other than that, looks like a great start!