0.2.1

Everything since v0.2.0, and the reason to update: connections no longer
go zombie.

Reliability

• Discarded SDK clients stopped retrying forever after a rejected
  connection — the endless "Socket error / Connection closed by host"
  pairs (and the phantom Disconnected while actually connected) are gone.
• Connection failures now report the real error ("Unexpected server
  response: 401") instead of a generic "Socket not open".
• Double registrations from stale clients driving service state: fixed.

Realm tokens

• Each remembered host carries its own keychain-encrypted token, so
  picking a past realm recalls that realm's token — no cross-realm
  fallback.
• Fixed a leak where a token from one realm could be prefilled and
  auto-connected into another.
• Unchecking "Remember token" now wipes stored tokens immediately, and a
  token you typed is never overwritten by an auto-filled one.

Build

• The Intel macOS .dmg is back: the x64 job now builds on macos-latest.
  v0.2.0 shipped without one because its runner had been retired.