fix: hover navbar, soporte sin spinner, RETHUS en formulario profesional

- Navbar: hoverColor tenue por tema (azul/blanco) en vez del gris por defecto de Flutter web
- SettingsProvider: lazy:false + timeout 10s para evitar spinner gris permanente en soporte
- SupportView: muestra contenido con defaults inmediatamente sin bloquear en isLoading
- Modelo Profesional: campos rethus_code y rethus_validated
- ProfessionalFormProvider: soporte para rethus_code en copyProfesionalWith
- RequestProfessionalView: campo RETHUS opcional en formulario + fix color dropdown profesión

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

lib/providers/professional_form_provider.dart

@@ -16,6 +16,7 @@ class ProfessionalFormProvider with ChangeNotifier {
   copyProfesionalWith({
     String? id,
     String? identification,
+    String? rethusCode,
     String? address,
     String? aditionalAddress,
     String? profession,
@@ -35,6 +36,7 @@ class ProfessionalFormProvider with ChangeNotifier {
     profesional = Profesional(
       id: id ?? profesional!.id,
       identification: identification ?? profesional!.identification,
+      rethusCode: rethusCode ?? profesional!.rethusCode,
       address: address ?? profesional!.address,
       aditionalAddress: aditionalAddress ?? profesional!.aditionalAddress,
       profession: profession ?? profesional!.profession,

lib/providers/settings_provider.dart

@@ -13,7 +13,7 @@ class SettingsProvider extends ChangeNotifier {
 
   getSettings() async {
     try {
-      final data = await _api.get('/settings');
+      final data = await _api.get('/settings').timeout(const Duration(seconds: 10));
       if (data != null) {
         settings = Setting.fromDocument(data as Map<String, dynamic>);
       }