Rolling build from main

The current build of main. Replaced on every push, so this download link is always
the newest APK. Not a released version — the Releases list has those.

• version 1.2 (10217)
• commit 89ca00d983b6bb707c65e2e88eb63b9336f6e730 — Cut 1.2: the release installs beside a development build
• run 35507347769

Signed with the production key, so it installs straight over a tagged release or an
earlier rolling build and the settings, certificates and recordings all survive. See
docs/install.md
for setting a phone up from scratch.