feat: SMS OTP auth + phone verification gate + improved login UI

- Usuario model: add isPhoneVerified field from is_phone_verified
- auth_provider.dart: fix access_token key, add _navigateAfterAuth gate
  (redirects to phoneLoginRoute if phone not verified), add verifyPhoneNumber,
  signInWithOTP, verifyPhoneNumberForLink, linkPhoneWithOTP methods
- phone_login_view.dart: full rewrite with logo, +57 prefix, two-step OTP flow
  (phone input → code input), 60s resend timer, email login fallback

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

lib/providers/auth_provider.dart

@@ -21,6 +21,14 @@ class AuthProvider extends ChangeNotifier {
     isAuthenticated();
   }
 
+  void _navigateAfterAuth() {
+    if (user?.isPhoneVerified == false) {
+      NavigationService.replaceTo(Flurorouter.phoneLoginRoute);
+    } else {
+      NavigationService.replaceTo(Flurorouter.dashboardRoute);
+    }
+  }
+
   Future<void> login(String email, String password) async {
     try {
       final data = await _api.post('/auth/login', {'email': email, 'password': password});
@@ -29,7 +37,7 @@ class AuthProvider extends ChangeNotifier {
       userAverageScore = await _loadAverageScore(user!.id);
       authStatus = AuthStatus.authenticated;
       notifyListeners();
-      NavigationService.replaceTo(Flurorouter.dashboardRoute);
+      _navigateAfterAuth();
     } catch (e) {
       authStatus = AuthStatus.notAuthenticated;
       notifyListeners();
@@ -48,7 +56,7 @@ class AuthProvider extends ChangeNotifier {
       user = Usuario.fromDocument(data['user'] as Map<String, dynamic>);
       authStatus = AuthStatus.authenticated;
       notifyListeners();
-      NavigationService.replaceTo(Flurorouter.dashboardRoute);
+      _navigateAfterAuth();
     } catch (e) {
       authStatus = AuthStatus.notAuthenticated;
       notifyListeners();
@@ -70,6 +78,7 @@ class AuthProvider extends ChangeNotifier {
       final data = await _api.post('/auth/phone', {'phone': phoneNumber, 'code': smsCode});
       await _api.saveToken(data['access_token'] as String);
       user = Usuario.fromDocument(data['user'] as Map<String, dynamic>);
+      userAverageScore = await _loadAverageScore(user!.id);
       authStatus = AuthStatus.authenticated;
       notifyListeners();
       NavigationService.replaceTo(Flurorouter.dashboardRoute);