feat(frontend): add API client, layout, and routing

- Create Axios-based API client with sources, jobs, and dashboard endpoints
- Add responsive Layout component with navigation sidebar
- Set up React Router with Dashboard, Backups, and Settings routes
- Configure TanStack Query provider with default options
- Use lucide-react for navigation icons

frontend/node_modules/lodash/_isMaskable.js

@@ -0,0 +1,14 @@
+var coreJsData = require('./_coreJsData'),
+    isFunction = require('./isFunction'),
+    stubFalse = require('./stubFalse');
+
+/**
+ * Checks if `func` is capable of being masked.
+ *
+ * @private
+ * @param {*} value The value to check.
+ * @returns {boolean} Returns `true` if `func` is maskable, else `false`.
+ */
+var isMaskable = coreJsData ? isFunction : stubFalse;
+
+module.exports = isMaskable;