v0.3.6 — opt-in debug logging.

• New: Debug Logging in Settings, off by default. If you hit a bug,
  turn it on, reproduce it, then Export to send us a diagnostic log.
  Your secrets are removed and your contacts' names become anonymous
  tags like <peer-1> before anything leaves your phone. It auto-erases
  after 24 hours, and a banner shows whenever it's recording.
• Contact names that look like Signet data are now rejected at
  pairing time, so a name can't be mistaken for a secret.

Issues: https://github.com/digital-grease/signet/issues.
