feat: module toggles in POS config and Instance Manager

- Add GET/PUT /pos/api/config/modules endpoints in POS config_bp.py
- Update sidebar.js to filter nav items based on enabled modules
- Add Modules section to POS config.html with toggles for WhatsApp, Marketplace, MercadoLibre
- Add module load/save logic to POS config.js
- Preload modules in app-init.js for sidebar caching

- Add tenant module management to Instance Manager
  - get_tenant_modules / update_tenant_modules in tenant_service.py
  - GET/PUT /api/tenants/<id>/modules endpoints in tenants_bp.py
  - Add modules modal to manager index.html
  - Add module editing UI and logic to manager.js
  - Add toggle-switch CSS to manager.css

manager/templates/index.html

@@ -316,6 +316,53 @@
         </div>
     </div>
 
+    <!-- Modules Modal -->
+    <div id="modules-modal" class="modal" style="display:none;">
+        <div class="modal-overlay" onclick="closeModulesModal()"></div>
+        <div class="modal-content" style="max-width:480px;">
+            <div class="modal-header">
+                <h3 id="modules-modal-title">Módulos del Tenant</h3>
+                <button class="btn-icon" onclick="closeModulesModal()"><i class="fas fa-times"></i></button>
+            </div>
+            <div class="modal-body">
+                <div class="form-group" style="display:flex;align-items:center;justify-content:space-between;padding:12px 0;border-bottom:1px solid var(--border);">
+                    <div>
+                        <div style="font-weight:600;color:var(--text);">WhatsApp</div>
+                        <div style="font-size:12px;color:var(--text-muted);">Mostrar menú de WhatsApp Bridge</div>
+                    </div>
+                    <label class="toggle-switch">
+                        <input type="checkbox" id="mod-whatsapp">
+                        <span class="toggle-slider"></span>
+                    </label>
+                </div>
+                <div class="form-group" style="display:flex;align-items:center;justify-content:space-between;padding:12px 0;border-bottom:1px solid var(--border);">
+                    <div>
+                        <div style="font-weight:600;color:var(--text);">Marketplace</div>
+                        <div style="font-size:12px;color:var(--text-muted);">Mostrar menú de Marketplace interno</div>
+                    </div>
+                    <label class="toggle-switch">
+                        <input type="checkbox" id="mod-marketplace">
+                        <span class="toggle-slider"></span>
+                    </label>
+                </div>
+                <div class="form-group" style="display:flex;align-items:center;justify-content:space-between;padding:12px 0;">
+                    <div>
+                        <div style="font-weight:600;color:var(--text);">MercadoLibre</div>
+                        <div style="font-size:12px;color:var(--text-muted);">Mostrar menú de MercadoLibre</div>
+                    </div>
+                    <label class="toggle-switch">
+                        <input type="checkbox" id="mod-meli">
+                        <span class="toggle-slider"></span>
+                    </label>
+                </div>
+            </div>
+            <div class="modal-footer">
+                <button class="btn btn-secondary" onclick="closeModulesModal()">Cancelar</button>
+                <button class="btn btn-primary" id="modules-save-btn" onclick="saveModules()">Guardar</button>
+            </div>
+        </div>
+    </div>
+
     <!-- Toast -->
     <div id="toast-container"></div>