Launcher mode: Gearslip as the home screen of a head unit or a dash tablet

Turned on under Settings > Connection, Gearslip's car screen fills the device's own
display as its home app. An All apps page opens any other app full screen, Back and
a head unit's keys work the car UI, and Phone hides on devices that can't call.
Phones never see Gearslip offered as a home app unless it's switched on.

gearslip/src/main/AndroidManifest.xml

@@ -160,6 +160,26 @@
 
         </activity>
 
+        <!--
+          Launcher mode: the car UI as this device's home screen, for a head unit that runs Android
+          or a tablet on the dash. Off until Settings turns it on (LauncherMode), so phones never
+          list Gearslip as a home app.
+        -->
+        <activity
+            android:name=".LauncherActivity"
+            android:enabled="false"
+            android:exported="true"
+            android:launchMode="singleTask"
+            android:excludeFromRecents="true"
+            android:screenOrientation="sensorLandscape"
+            android:configChanges="orientation|screenSize|screenLayout|smallestScreenSize|keyboardHidden|uiMode|density|locale|layoutDirection|fontScale">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.HOME" />
+                <category android:name="android.intent.category.DEFAULT" />
+            </intent-filter>
+        </activity>
+
         <!--
           Answers the car's USB connection on GearslipActivity's behalf. Kept apart from the
           activity so Settings can switch off just this (AppSettings.setGearslipEnabled) and leave