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/test/features/auth/presentation/bloc/auth_bloc_test.dart

@@ -50,7 +50,7 @@ void main() {
             refreshToken: 'new_refresh',
             expiresIn: 3600,
             tokenType: 'bearer',
-            user: const AuthUser(id: '123', email: 'test@example.com'),
+            user: const AuthUser(id: '123', phone: '+8613812345678'),
           ),
         );
         return authBloc;
@@ -107,7 +107,7 @@ void main() {
       build: () => authBloc,
       act: (bloc) => bloc.add(
         AuthLoggedIn(
-          user: const AuthUser(id: '1', email: 'test@example.com'),
+          user: const AuthUser(id: '1', phone: '+8613812345678'),
         ),
       ),
       expect: () => [isA<AuthAuthenticated>()],
@@ -120,7 +120,7 @@ void main() {
         return authBloc;
       },
       seed: () => AuthAuthenticated(
-        user: const AuthUser(id: '1', email: 'test@example.com'),
+        user: const AuthUser(id: '1', phone: '+8613812345678'),
       ),
       act: (bloc) => bloc.add(AuthLoggedOut()),
       expect: () => [
@@ -137,7 +137,7 @@ void main() {
         return authBloc;
       },
       seed: () => AuthAuthenticated(
-        user: const AuthUser(id: '1', email: 'test@example.com'),
+        user: const AuthUser(id: '1', phone: '+8613812345678'),
       ),
       act: (bloc) => bloc.add(
         const AuthSessionInvalidated(