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/@babel/runtime/helpers/importDeferProxy.js

@@ -0,0 +1,27 @@
+function _importDeferProxy(e) {
+  var t = null,
+    constValue = function constValue(e) {
+      return function () {
+        return e;
+      };
+    },
+    proxy = function proxy(r) {
+      return function (n, o, f) {
+        return null === t && (t = e()), r(t, o, f);
+      };
+    };
+  return new Proxy({}, {
+    defineProperty: constValue(!1),
+    deleteProperty: constValue(!1),
+    get: proxy(Reflect.get),
+    getOwnPropertyDescriptor: proxy(Reflect.getOwnPropertyDescriptor),
+    getPrototypeOf: constValue(null),
+    isExtensible: constValue(!1),
+    has: proxy(Reflect.has),
+    ownKeys: proxy(Reflect.ownKeys),
+    preventExtensions: constValue(!0),
+    set: constValue(!1),
+    setPrototypeOf: constValue(!1)
+  });
+}
+module.exports = _importDeferProxy, module.exports.__esModule = true, module.exports["default"] = module.exports;