clickable hashtags (searchable topics) #78

i see many posts with #hashtags like this one:

would be nice to support this. it's NIP-12, i believe, with t in the filters object.

i see many posts with `#hashtag`s like this one: ![image](/attachments/2b17297d-5dee-4bdb-a6a2-e12959cf4181) would be nice to support this. it's [NIP-12](https://github.com/nostr-protocol/nips/blob/461b4bb1/12.md), i believe, with `t` in the filters object.