feat: SMS OTP phone auth + mandatory phone verification gate

- MyUser: add isPhoneVerified field (from is_phone_verified in API)
- ApiUserRepository: signInWithPhoneNumber calls POST /auth/send-otp,
  verifyOTP calls POST /auth/phone, linkWithOTP calls POST /auth/verify-phone
  Added updateFcmToken and changePassword methods
- AuthBloc: remove Firebase PhoneVerificationService, use repository OTP flow
- app_view.dart: gate authenticated users without verified phone to
  PhoneVerifyRequiredScreen before showing HomeScreen
- welcome_screen.dart: full redesign with gradient header, logo, integrated
  OTP flow (phone → code in same screen), 60s resend timer
- PhoneVerifyRequiredScreen: new screen for users who need to verify phone

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/app_view.dart

@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:prosappco/blocs/notification_bloc/notification_bloc.dart';
 import 'package:prosappco/screens/authentication/welcome_screen.dart';
+import 'package:prosappco/screens/authentication/phone_verify_required_screen.dart';
 import 'package:prosappco/screens/home/home_screen.dart';
 import 'package:prosappco/screens/splash/splash_screen.dart';
 import 'package:flutter_localizations/flutter_localizations.dart';
@@ -44,19 +45,23 @@ class MyAppView extends StatelessWidget {
           }
         },
         builder: (context, state) {
-          return getScreen(state);
+          return _getScreen(state);
         },
       ),
     );
   }
 
-  getScreen(AuthenticationState state) {
+  Widget _getScreen(AuthenticationState state) {
     switch (state.status) {
       case AuthenticationStatus.authenticated:
+        final phoneVerified = state.user?.isPhoneVerified ?? false;
+        if (!phoneVerified) {
+          return PhoneVerifyRequiredScreen(phone: state.user?.phone);
+        }
         return HomeScreen();
 
       case AuthenticationStatus.unauthenticated:
-        return WelcomeScreen();
+        return const WelcomeScreen();
 
       case AuthenticationStatus.unknown:
         return const SplashScreen();