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/blueprints/tenants_bp.py

@@ -58,3 +58,24 @@ def delete_tenant(tenant_id):
         return jsonify(result)
     except Exception as e:
         return jsonify({"error": str(e)}), 500
+
+
+@tenants_bp.route("/<int:tenant_id>/modules", methods=["GET"])
+@require_manager_auth
+def get_tenant_modules(tenant_id):
+    try:
+        result = tenant_service.get_tenant_modules(tenant_id)
+        return jsonify({"data": result})
+    except Exception as e:
+        return jsonify({"error": str(e)}), 500
+
+
+@tenants_bp.route("/<int:tenant_id>/modules", methods=["PUT"])
+@require_manager_auth
+def update_tenant_modules(tenant_id):
+    data = request.get_json() or {}
+    try:
+        result = tenant_service.update_tenant_modules(tenant_id, data)
+        return jsonify(result)
+    except Exception as e:
+        return jsonify({"error": str(e)}), 500