[Feature Request] Mentions, Changing handle, Hashtags, and trendings hashtags

[FoxTale-Labs]

I want to add the following features to the site as well as some general polish while I'm at it to fix some bugs like notifications not updating properly, QoL improvements like when u delete a post it doesnt go away from your view, refresh issues, probably, etc.
Would that be ok?

[face-hh]

Sure but I suggest waiting for #20 to be merged since it will have a lot of changes