opt-in usage notes and a stats dashboard

Release builds ask in setup and Settings whether to send a short note when the app is opened and after each drive: the version, plus the Android version, phone model and cars people tick. Nothing runs in the background. Dev builds always send. The Cloudflare Worker in stats-worker/ stores the notes and serves a private dashboard with GitHub downloads alongside.

gradle.properties

@@ -21,4 +21,6 @@ kotlin.code.style=official
 # resources declared in the library itself and none from the library's dependencies,
 # thereby reducing the size of the R class for that library
 android.nonTransitiveRClass=true
-android.dependency.useConstraints=false
+android.dependency.useConstraints=false
+# Where opted-in phones send their daily usage note (stats-worker/). Blank sends nothing.
+gearslipStatsUrl=https://gearslip-stats.gearslip.workers.dev