refactor(auth): remove requestCodeCooldown status

Refactored the authentication BLoC and UI to rely solely on the `cooldownEndTime` timestamp for managing the sign-in code request cooldown. This removes the redundant `requestCodeCooldown` from the `AuthenticationStatus` enum, simplifying the state machine and establishing a single source of truth for the cooldown logic.

This change fixes the bug where the cooldown timer would not display correctly after a failed verification and makes the implementation more robust and maintainable.

Author: fulleni

lib/authentication/bloc/authentication_bloc.dart

@@ -76,7 +76,10 @@ class AuthenticationBloc
     Emitter<AuthenticationState> emit,
   ) async {
     // Prevent request if already in cooldown
-    if (state.status == AuthenticationStatus.requestCodeCooldown) return;
+    if (state.cooldownEndTime != null &&
+        state.cooldownEndTime!.isAfter(DateTime.now())) {
+      return;
+    }
 
     emit(state.copyWith(status: AuthenticationStatus.requestCodeLoading));
     try {
@@ -92,9 +95,6 @@ class AuthenticationBloc
           cooldownEndTime: cooldownEndTime,
         ),
       );
-      // Transition to cooldown state after a brief moment
-      await Future<void>.delayed(const Duration(milliseconds: 100));
-      emit(state.copyWith(status: AuthenticationStatus.requestCodeCooldown));
 
       // Start a timer to transition out of cooldown
       Timer(
@@ -202,14 +202,12 @@ class AuthenticationBloc
     AuthenticationCooldownCompleted event,
     Emitter<AuthenticationState> emit,
   ) {
-    if (state.status == AuthenticationStatus.requestCodeCooldown) {
-      emit(
-        state.copyWith(
-          status: AuthenticationStatus.initial,
-          clearCooldownEndTime: true,
-        ),
-      );
-    }
+    emit(
+      state.copyWith(
+        status: AuthenticationStatus.initial,
+        clearCooldownEndTime: true,
+      ),
+    );
   }
 
   @override

lib/authentication/bloc/authentication_state.dart

@@ -22,9 +22,6 @@ enum AuthenticationStatus {
   /// The sign-in code was sent successfully.
   codeSentSuccess,
 
-  /// The user is in a cooldown period after requesting a code.
-  requestCodeCooldown,
-
   /// An authentication operation failed.
   failure,
 }

lib/authentication/view/request_code_page.dart

@@ -248,9 +248,11 @@ class _EmailLinkFormState extends State<_EmailLinkForm> {
     final colorScheme = Theme.of(context).colorScheme;
 
     return BlocListener<AuthenticationBloc, AuthenticationState>(
+      listenWhen: (previous, current) =>
+          previous.cooldownEndTime != current.cooldownEndTime,
       listener: (context, state) {
-        if (state.status == AuthenticationStatus.requestCodeCooldown &&
-            state.cooldownEndTime != null) {
+        if (state.cooldownEndTime != null &&
+            state.cooldownEndTime!.isAfter(DateTime.now())) {
           _cooldownTimer?.cancel();
           _startCooldownTimer(state.cooldownEndTime!);
         }