Melarka 0.2.21

Added

• An opt-in anonymous install count (Admin → System, off by default). When an admin turns it on, the
  server sends a random install number and its version to melarka.zexa.se about once a week, so the project
  can count how many homes run Melarka. Nothing else is sent; turning it off deletes the number.

Changed

• Updated dependencies: the SQLite driver (1.61.1), the Go, Node and Alpine base images, and the web
  app's test tools.
• Installing the iPhone app with a Mac no longer needs SideStore first. ios/scripts/resign.sh
  reads the Apple ID's team from Xcode when Melarka is not on the phone yet, so a Mac with Xcode can
  do the first install and then keep the app signed. docs/iphone.md now starts with this route.