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/ui/views/request_professional_view.dart

@@ -157,6 +157,19 @@ class _ProfileViewFormState extends State<_ProfileViewForm> {
                         ),
                       ),
                       const SizedBox(height: 10),
+                      TextFormField(
+                        initialValue: professional!.rethusCode,
+                        onChanged: (value) {
+                          professionalFormProvider.copyProfesionalWith(
+                              rethusCode: value);
+                        },
+                        decoration: CustomInputs.formInputDecoration(
+                          hint: 'Código RETHUS (opcional)',
+                          label: 'Código RETHUS',
+                          icon: Icons.health_and_safety_outlined,
+                        ),
+                      ),
+                      const SizedBox(height: 10),
                       ElevatedButton.icon(
                         onPressed: () async {
                           try {
@@ -210,13 +223,7 @@ class _ProfileViewFormState extends State<_ProfileViewForm> {
                           items: professions.map((Profession profession) {
                             return DropdownMenuItem<String>(
                               value: profession.name,
-                              child: Text(
-                                profession.name,
-                                style: const TextStyle(
-                                  color: Colors.black,
-                                  fontWeight: FontWeight.normal,
-                                ),
-                              ),
+                              child: Text(profession.name),
                             );
                           }).toList(),
                           onChanged: (value) {