feat: use the pubky.app profile directly #1864

Bitkit and pubky.app should share one profile: Bitkit reads and edits the user's own pubky.app profile (/pub/pubky.app/profile.json) directly instead of keeping its own.

Done in #1801 (twin: synonymdev/bitkit-ios#1235), on Paykit 0.1.1-rc7 from pubky/paykit-rs#270.