feat(auth): transition from email to phone-based OTP authentication

- Replace Email+Password login with Phone+OTP flow
- Remove RegisterCubit and registration screens (email verification)
- Remove ResetPasswordCubit and reset password screens
- Add phone normalization and international dial code support
- Update LoginCubit with sendCode/resend cooldown logic
- Add new widgets: phone prefix selector, confirm sheet
- Update all auth API endpoints: /otp/send, /phone-session
- Update form inputs: Email -> Phone with E.164 validation
- Update tests for new auth flow

apps/lib/features/auth/data/models/auth_response.dart

@@ -1,11 +1,11 @@
 class AuthUser {
   final String id;
-  final String email;
+  final String phone;
 
-  const AuthUser({required this.id, required this.email});
+  const AuthUser({required this.id, required this.phone});
 
   factory AuthUser.fromJson(Map<String, dynamic> json) {
-    return AuthUser(id: json['id'] as String, email: json['email'] as String);
+    return AuthUser(id: json['id'] as String, phone: json['phone'] as String);
   }
 }
 
@@ -34,13 +34,3 @@ class AuthResponse {
     );
   }
 }
-
-class VerificationCreateResponse {
-  final String email;
-
-  const VerificationCreateResponse({required this.email});
-
-  factory VerificationCreateResponse.fromJson(Map<String, dynamic> json) {
-    return VerificationCreateResponse(email: json['email'] as String);
-  }
-}