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/_hashHas.js

@@ -0,0 +1,23 @@
+var nativeCreate = require('./_nativeCreate');
+
+/** Used for built-in method references. */
+var objectProto = Object.prototype;
+
+/** Used to check objects for own properties. */
+var hasOwnProperty = objectProto.hasOwnProperty;
+
+/**
+ * Checks if a hash value for `key` exists.
+ *
+ * @private
+ * @name has
+ * @memberOf Hash
+ * @param {string} key The key of the entry to check.
+ * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
+ */
+function hashHas(key) {
+  var data = this.__data__;
+  return nativeCreate ? (data[key] !== undefined) : hasOwnProperty.call(data, key);
+}
+
+module.exports = hashHas;