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/_listCacheGet.js

@@ -0,0 +1,19 @@
+var assocIndexOf = require('./_assocIndexOf');
+
+/**
+ * Gets the list cache value for `key`.
+ *
+ * @private
+ * @name get
+ * @memberOf ListCache
+ * @param {string} key The key of the value to get.
+ * @returns {*} Returns the entry value.
+ */
+function listCacheGet(key) {
+  var data = this.__data__,
+      index = assocIndexOf(data, key);
+
+  return index < 0 ? undefined : data[index][1];
+}
+
+module.exports = listCacheGet;