Packaging fix. The v0.2.2 downloads carried a build-tool metadata block that
F-Droid does not accept, so the reproducible build could not be verified; it is
now switched off. Per-architecture downloads are also named by architecture
(arm64-v8a, armeabi-v7a, x86_64) instead of by build number, so you can tell
which file you need. No app behaviour change.
