Android: GATT read/write failures are reported as success

[qdot]

src/droidplug/java/.../Peripheral.java onCharacteristicRead, onCharacteristicWrite, onDescriptorRead, onDescriptorWrite command callbacks never check status.

Failure scenario: write() to a characteristic requiring encryption gets GATT_INSUFFICIENT_AUTHENTICATION and returns Ok(()); a failed read() returns stale/empty bytes as Ok. Violates the Peripheral::write contract ("error ... if the device returns an error").

Fix direction: fail the future when status != GATT_SUCCESS, including the status code in the error.