Change URL behavior (parse the content to the url)

I think it's better to take inspiration from Vue SFC playground.
It seems like it creates a hash for the content, and parse it inside it's ReplStore. See https://github.com/vuejs/core/tree/main/packages/sfc-playground
This will make the link is a Bijective function to the content. Which means that we can create cool stuff like programmatically embed content to the url - like in https://github.com/LinusBorg/slidev-theme-vuetiful/blob/348090dff814bb97f835c2944daaf2fd77552d83/layouts/sfc.vue#L32 - the component embed its content programmatically so the content code is readable before injecting it into the url - and we can extract it from the url. The url get const encoded = window.btoa(JSON.stringify(content)) so we can do the reverse with const decodedString = JSON.parse(window.atob(encoded)).
This may affect the way the URL handles now with tokens and anonymous users and the behavior of the share button will be just to copy the URL instead of saving.
This issue is related to #105

Start by reading related issue #105 and the Vue SFC playground ReplStore linked in the issue. Then inspect the current URL, token, anonymous-user, and share-button behavior. Done requires an agreed content-to-URL round trip and clarified effects on existing sharing and token behavior.