fix(android): move MainActivity to the package the manifest looks for

The app crashed on launch with ClassNotFoundException for
es.freetimelab.farolero.game.MainActivity: 374c6ae added the .game suffix to
namespace and applicationId but left the Kotlin source in
es.freetimelab.farolero, so the manifest asked for a class that was never
compiled under that name. Every release built since then died on startup,
including the one already published to internal testing.

Also requests edge-to-edge explicitly now that the app targets 35, rather
than relying on the Flutter default.

Verified on a physical device running Android 16: installs, launches and
stays alive with no crash, and the bottom action buttons sit clear of the
navigation bar.

android/app/src/main/kotlin/es/freetimelab/farolero/game/MainActivity.kt

@@ -1,4 +1,4 @@
-package es.freetimelab.farolero
+package es.freetimelab.farolero.game
 
 import io.flutter.embedding.android.FlutterActivity