Use material 3 page transitions [android] (#267)

The latest version of flutter (3.29, which we're already using) finally added a decent page transition matching up with the native material 3 transition. (main-api.flutter.dev/flutter/material/FadeForwardsPageTransitionsBuilder-class.html)

To test, fire up the app in android, and navigate around.

lib/services/theme.dart

@@ -345,6 +345,12 @@ class MaterialTheme {
     textTheme: textTheme.apply(bodyColor: colorScheme.onSurface, displayColor: colorScheme.onSurface),
     scaffoldBackgroundColor: colorScheme.surface,
     canvasColor: colorScheme.surface,
+    pageTransitionsTheme: PageTransitionsTheme(
+      builders: Map<TargetPlatform, PageTransitionsBuilder>.fromIterable(
+        TargetPlatform.values,
+        value: (_) => const FadeForwardsPageTransitionsBuilder(),
+      ),
+    ),
   );
 
   List<ExtendedColor> get extendedColors => [];