fix(ui): resolver superposicion en menu colapsado, reparar edicion de ciclo lectivo, aplicar paleta UniCABA y agregar control de modo demo en config global

backend/app/routes/auth.py

@@ -16,6 +16,9 @@ def login():
     if current_user.is_authenticated:
         return redirect(url_for('main.dashboard'))
     
+    from app.models.setting import SystemSetting
+    demo_access_enabled = SystemSetting.get_value('demo_access_enabled', 'true') in ['true', 'True', '1', True]
+    
     form = LoginForm()
     if form.validate_on_submit():
         clean_email = (form.email.data or '').strip().lower()
@@ -24,7 +27,7 @@ def login():
         if user and user.check_password(form.password.data):
             if not user.is_active:
                 flash(_('Tu cuenta ha sido desactivada. Por favor contacta al administrador.'), 'error')
-                return render_template('auth/login.html', form=form)
+                return render_template('auth/login.html', form=form, demo_access_enabled=demo_access_enabled)
             
             login_user(user, remember=form.remember_me.data)
             user.update_last_login()
@@ -69,7 +72,7 @@ def login():
                 pass
             flash(_('Correo electrónico o contraseña inválidos.'), 'error')
     
-    return render_template('auth/login.html', form=form)
+    return render_template('auth/login.html', form=form, demo_access_enabled=demo_access_enabled)
 
 @auth_bp.route('/logout')
 @login_required