v0.3.4

New: in-app crash reporter. If the app crashes, the next launch
offers to file a pre-filled GitHub Issue with the stack trace.
Cryptographic material (paired secrets, verify codes, backup
payloads, contact labels) is redacted on-device before anything
leaves your phone. No in-process network — "File issue" opens
your OS browser.

Fixed: in-person pairing deadlock (#1). Both devices now wait for
both scan + show before advancing to verification.
