I think it's up to clients to add file extensions nostr:nprofile1qqsyvrp9u6p0mfur9dfdru3d853tx9mdjuhkphxuxgfwmryja7zsvhqppemhxue69uhkummn9ekx7mp0qythwumn8ghj7anfw3hhytnwdaehgu339e3k7mf0qyghwumn8ghj7mn0wd68ytnhd9hx2tch2deau kind 1 posts require it for parsing