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/@testing-library/dom/dist/get-node-text.js

@@ -0,0 +1,13 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.getNodeText = getNodeText;
+var _helpers = require("./helpers");
+function getNodeText(node) {
+  if (node.matches('input[type=submit], input[type=button], input[type=reset]')) {
+    return node.value;
+  }
+  return Array.from(node.childNodes).filter(child => child.nodeType === _helpers.TEXT_NODE && Boolean(child.textContent)).map(c => c.textContent).join('');
+}