Expand the post system

[MenschlichDE]

Expand the post system by adding:

• Search allow us to search for posts like msg search
• Tags so we can search by tag we like
• Reactions like how we can react to msgs
• Quote posts, allowing users to repost content with their own commentary
• Community posts, enabling servers to publish announcement-style posts; servers should be followable so users can receive updates from a server yk? maybe add another tab for servers in feed??

[IvySmolOri]

I think we could do with Tags being added to posts

[Angreyna]

Would be really cool to be able to have at least tags ^^