feat: Add email configuration and alert system

Introduces SMTP configuration settings and alert definitions to enable automated email notifications.
This includes new types for `SmtpConfig` and `AlertDefinition`, and integrates these into the settings page and mock database.
Adds styling for select elements and scrollbar hiding in the main HTML.
Updates mock database logic to potentially support local development without a backend.

components/Layout.tsx

@@ -12,7 +12,7 @@ export const Layout: React.FC = () => {
     `flex items-center gap-3 px-4 py-3 rounded-lg transition-all duration-200 ${
       isActive
         ? 'bg-blue-600 text-white shadow-md'
-        : 'text-slate-600 hover:bg-slate-100'
+        : 'text-slate-600 hover:text-slate-900 hover:bg-slate-100'
     }`;
 
   const closeMenu = () => setIsMobileMenuOpen(false);
@@ -66,12 +66,10 @@ export const Layout: React.FC = () => {
             <span className="font-medium">Famiglie</span>
           </NavLink>
           
-          {isAdmin && (
-            <NavLink to="/settings" className={navClass} onClick={closeMenu}>
-              <Settings className="w-5 h-5" />
-              <span className="font-medium">Impostazioni</span>
-            </NavLink>
-          )}
+          <NavLink to="/settings" className={navClass} onClick={closeMenu}>
+            <Settings className="w-5 h-5" />
+            <span className="font-medium">Impostazioni</span>
+          </NavLink>
         </nav>
 
         <div className="p-4 border-t border-slate-100 bg-slate-50/50">