[feat]: roadmap towards v1 stable specs

[SHAcollision]

There has been a lot of learning with current v0 specs. We can keep working our way towards the first stable version. This issue contains a list of detected TODOs that MUST be completed before v1:

• Add v1 version on top level /pubky.app/v1/
• Add versioning to posts for history of edits, for example /pubky.app/v1/posts/{post_id}/0 would be the first version of the post (notice the final /0). We could encode the version with crockford for shorter URLs in the unlikely case of big versions (e.g articles that become a "wiki" and have many edits).
• Add PubkyId type and validation. #14
• Remove fields that are unused in practice. Remove PostEmbed model and replace with just a String for the uri. Remove unused fields from File as well.
• Add an URI parser that will extract PostID or TagId etc from a given URI. Consider bringing in https://github.com/pubky/pubky-nexus/blob/main/src/events/uri.rs Add uri parser and object importer #15
• Add a method that given a URI and a Blob from the homeserver, will return a fully formed PubkyAppObject . Consider bringing https://github.com/pubky/pubky-nexus/blob/main/src/events/mod.rs Add uri parser and object importer #15
• Remove pub fields and use getters/setters where needed.
• Research where else we can simplify to the max.