Enhance role selection dropdown with custom InkWell and update dropdown color

b0esche_cloud/lib/widgets/organization_settings_dialog.dart

@@ -560,8 +560,17 @@ class _OrganizationSettingsDialogState
               child: DropdownButtonFormField<String>(
                 initialValue: selectedRole,
                 items: ['admin', 'member'].map((role) {
-                  return DropdownMenuItem(value: role, child: Text(role));
+                  return DropdownMenuItem(
+                    value: role,
+                    child: InkWell(
+                      splashFactory: NoSplash.splashFactory,
+                      highlightColor: Colors.transparent,
+                      splashColor: Colors.transparent,
+                      child: Text(role),
+                    ),
+                  );
                 }).toList(),
+                dropdownColor: AppTheme.primaryBackground,
                 onChanged: (value) => selectedRole = value ?? 'member',
                 decoration: InputDecoration(
                   labelText: 'Role',