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/_shortOut.js

@@ -0,0 +1,37 @@
+/** Used to detect hot functions by number of calls within a span of milliseconds. */
+var HOT_COUNT = 800,
+    HOT_SPAN = 16;
+
+/* Built-in method references for those with the same name as other `lodash` methods. */
+var nativeNow = Date.now;
+
+/**
+ * Creates a function that'll short out and invoke `identity` instead
+ * of `func` when it's called `HOT_COUNT` or more times in `HOT_SPAN`
+ * milliseconds.
+ *
+ * @private
+ * @param {Function} func The function to restrict.
+ * @returns {Function} Returns the new shortable function.
+ */
+function shortOut(func) {
+  var count = 0,
+      lastCalled = 0;
+
+  return function() {
+    var stamp = nativeNow(),
+        remaining = HOT_SPAN - (stamp - lastCalled);
+
+    lastCalled = stamp;
+    if (remaining > 0) {
+      if (++count >= HOT_COUNT) {
+        return arguments[0];
+      }
+    } else {
+      count = 0;
+    }
+    return func.apply(undefined, arguments);
+  };
+}
+
+module.exports = shortOut;