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/autoprefixer/lib/vendor.js

@@ -0,0 +1,14 @@
+module.exports = {
+  prefix(prop) {
+    let match = prop.match(/^(-\w+-)/)
+    if (match) {
+      return match[0]
+    }
+
+    return ''
+  },
+
+  unprefixed(prop) {
+    return prop.replace(/^-\w+-/, '')
+  }
+}