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/universalify/index.js

@@ -0,0 +1,29 @@
+'use strict'
+
+exports.fromCallback = function (fn) {
+  return Object.defineProperty(function () {
+    if (typeof arguments[arguments.length - 1] === 'function') fn.apply(this, arguments)
+    else {
+      return new Promise((resolve, reject) => {
+        arguments[arguments.length] = (err, res) => {
+          if (err) return reject(err)
+          resolve(res)
+        }
+        arguments.length++
+        fn.apply(this, arguments)
+      })
+    }
+  }, 'name', { value: fn.name })
+}
+
+exports.fromPromise = function (fn) {
+  return Object.defineProperty(function () {
+    const cb = arguments[arguments.length - 1]
+    if (typeof cb !== 'function') return fn.apply(this, arguments)
+    else {
+      delete arguments[arguments.length - 1]
+      arguments.length--
+      fn.apply(this, arguments).then(r => cb(null, r), cb)
+    }
+  }, 'name', { value: fn.name })
+}