refactor(router): simplify AccountLinking page transition

- Remove CustomTransitionPage for modal bottom sheet presentation
- Revert to using a simpler builder function for AccountLinking route
- This change reduces complexity and improves performance for account linking flow

Author: fulleni

lib/router/router.dart

@@ -201,29 +201,12 @@ GoRouter createRouter({
       GoRoute(
         path: Routes.accountLinking,
         name: Routes.accountLinkingName,
-        // Use CustomTransitionPage to create a modal bottom sheet presentation.
-        pageBuilder: (context, state) {
-          return CustomTransitionPage<void>(
-            // Set opaque to false to allow the underlying page to be visible.
-            opaque: false,
-            // Allow dismissing the modal by tapping outside the sheet.
-            barrierDismissible: true,
-            // Define the slide-up transition for the modal bottom sheet.
-            transitionsBuilder: (context, animation, secondaryAnimation, child) {
-              return SlideTransition(
-                position: Tween<Offset>(
-                  begin: const Offset(0, 1), // Start from bottom
-                  end: Offset.zero, // Slide to its final position
-                ).animate(animation),
-                child: child,
-              );
-            },
-            child: BlocProvider(
-              create: (context) => AuthenticationBloc(
-                authenticationRepository: context.read<AuthRepository>(),
-              ),
-              child: const AccountLinkingPage(),
+        builder: (context, state) {
+          return BlocProvider(
+            create: (context) => AuthenticationBloc(
+              authenticationRepository: context.read<AuthRepository>(),
             ),
+            child: const AccountLinkingPage(),
           );
         },
         routes: [