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/react/dist/config.js

@@ -0,0 +1,33 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.configure = configure;
+exports.getConfig = getConfig;
+var _dom = require("@testing-library/dom");
+let configForRTL = {
+  reactStrictMode: false
+};
+function getConfig() {
+  return {
+    ...(0, _dom.getConfig)(),
+    ...configForRTL
+  };
+}
+function configure(newConfig) {
+  if (typeof newConfig === 'function') {
+    // Pass the existing config out to the provided function
+    // and accept a delta in return
+    newConfig = newConfig(getConfig());
+  }
+  const {
+    reactStrictMode,
+    ...configForDTL
+  } = newConfig;
+  (0, _dom.configure)(configForDTL);
+  configForRTL = {
+    ...configForRTL,
+    reactStrictMode
+  };
+}