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/dom-helpers/esm/triggerEvent.js

@@ -0,0 +1,23 @@
+/**
+ * Triggers an event on a given element.
+ * 
+ * @param node the element
+ * @param eventName the event name to trigger
+ * @param bubbles whether the event should bubble up
+ * @param cancelable whether the event should be cancelable
+ */
+export default function triggerEvent(node, eventName, bubbles, cancelable) {
+  if (bubbles === void 0) {
+    bubbles = false;
+  }
+
+  if (cancelable === void 0) {
+    cancelable = true;
+  }
+
+  if (node) {
+    var event = document.createEvent('HTMLEvents');
+    event.initEvent(eventName, bubbles, cancelable);
+    node.dispatchEvent(event);
+  }
+}