Fry Android App v0.1.1

Reliability fixes found by code review after v0.1.0 was tagged. Upgrade is recommended;
v0.1.0 has a wallet-integrity bug under a specific but realistic condition.

• Provisioning writes could be silently truncated when the device refused the requested
  Bluetooth MTU. A 58-character wallet address would go out shortened, so the device could be
  provisioned with an address the user never entered. The app now tracks the negotiated MTU and
  performs a prepared write when the value will not fit a single packet, aborting rather than
  committing a partial value.
• The Bluetooth connection handle leaked if you left the provisioning screen mid-connection.
  Android allows only a small number of concurrent connections, so repeating that eventually
  broke all Bluetooth connections until Bluetooth was turned off and on again.
• The Wi-Fi network callback leaked on the same path, which could leave the phone pinned to the
  device's setup network with no internet.
• An unrecognised status byte from a device crashed the app. It is now ignored and reported.

16 unit tests pass. Verified on a Samsung S22.