refactor: remove ink well fill

lib/select_character/view/character_selection_page.dart

@@ -132,10 +132,15 @@ class _Character extends StatelessWidget {
   Widget build(BuildContext context) {
     return Expanded(
       child: Opacity(
-        opacity: isSelected ? 1 : 0.3,
+        opacity: isSelected ? 1 : 0.4,
         child: TextButton(
           onPressed: () =>
               context.read<CharacterThemeCubit>().characterSelected(character),
+          style: ButtonStyle(
+            overlayColor: MaterialStateProperty.all(
+              PinballColors.transparent,
+            ),
+          ),
           child: character.icon.image(fit: BoxFit.contain),
         ),
       ),

packages/pinball_ui/lib/src/widgets/pinball_button.dart

@@ -32,6 +32,8 @@ class PinballButton extends StatelessWidget {
         child: Center(
           child: InkWell(
             onTap: onTap,
+            splashColor: PinballColors.transparent,
+            highlightColor: PinballColors.transparent,
             child: Padding(
               padding: const EdgeInsets.symmetric(
                 horizontal: 32,

packages/pinball_ui/lib/src/widgets/pinball_dpad_button.dart

@@ -55,6 +55,8 @@ class PinballDpadButton extends StatelessWidget {
       color: PinballColors.transparent,
       child: InkWell(
         onTap: onTap,
+        splashColor: PinballColors.transparent,
+        highlightColor: PinballColors.transparent,
         child: Image.asset(
           direction.toAsset(),
           width: 60,