Update SettingsPage to replace notifications with language preference

Replaced the deprecated notifications option with a language selector in `SettingsPage`. Updated localStorage parsing to strip deprecated fields and added UI support for the new language preference.

src/components/Settings/SettingsPage.js

@@ -5,7 +5,7 @@ import '../../styles/components.css';
 const DEFAULT_SETTINGS = {
   timezone: Intl.DateTimeFormat().resolvedOptions().timeZone || 'UTC',
   theme: 'light',
-  notifications: true,
+  language: 'es',
   apiBaseUrl: ''
 };
 
@@ -14,7 +14,9 @@ const loadSettings = () => {
     const raw = localStorage.getItem('app_settings');
     if (!raw) return DEFAULT_SETTINGS;
     const parsed = JSON.parse(raw);
-    return { ...DEFAULT_SETTINGS, ...parsed };
+    // Strip deprecated fields like 'notifications' if present in older storage
+    const { notifications, ...rest } = parsed || {};
+    return { ...DEFAULT_SETTINGS, ...rest };
   } catch {
     return DEFAULT_SETTINGS;
   }
@@ -99,15 +101,11 @@ const SettingsPage = () => {
               </div>
 
               <div className="form-group">
-                <label className="checkbox">
-                  <input
-                    type="checkbox"
-                    name="notifications"
-                    checked={settings.notifications}
-                    onChange={handleChange}
-                  />
-                  Habilitar notificaciones
-                </label>
+                <label htmlFor="language">Idioma</label>
+                <select id="language" name="language" value={settings.language} onChange={handleChange}>
+                  <option value="es">Español</option>
+                  <option value="en">English</option>
+                </select>
               </div>
 
               <div className="form-group" style={{ gridColumn: '1 / -1' }}>