v0.2.0: phone app

Adds a phone app, so the watch no longer needs to be rebuilt or kept in debugging mode.

• Paste the snapshot URL into the phone app once. The phone sends it and fresh numbers to the watch over Bluetooth every 15 minutes.
• The watch asks the phone first when you tap refresh, and downloads directly over Wi-Fi or LTE when the phone is out of reach.
• Install the watch app once over adb, then turn ADB debugging and Wireless debugging off again. They drain the battery and the app does not need them.

Install both APKs from this release. They are signed with the same key, which the phone and watch need to talk to each other. If you have an older test build on the watch, remove it first with adb uninstall io.github.whyater.wristusage.

This is a pre-release: the phone-to-watch sync has only been tested in parts on emulators, not yet on a real phone and Galaxy Watch.