Add phone call handling on the car screen

Incoming calls now show the caller (name via contacts, else number) on
the car UI with answer/decline, using a call screening service so the
car sees a call before it rings. Also adds pinnable nav bar shortcuts,
lowers minSdk to 31 for wider device support, and bumps to 0.0.04-pre.

gearslip/build.gradle.kts

@@ -30,10 +30,10 @@ android {
 
     defaultConfig {
         applicationId = "app.seb3thehacker.gearslip"
-        minSdk = 35
+        minSdk = 31
         targetSdk = 37
-        versionCode = 3
-        versionName = "0.0.03-pre"
+        versionCode = 4
+        versionName = "0.0.04-pre"
     }
 
     signingConfigs {