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/loose-envify/cli.js

@@ -0,0 +1,16 @@
+#!/usr/bin/env node
+'use strict';
+
+var looseEnvify = require('./');
+var fs = require('fs');
+
+if (process.argv[2]) {
+  fs.createReadStream(process.argv[2], {encoding: 'utf8'})
+    .pipe(looseEnvify(process.argv[2]))
+    .pipe(process.stdout);
+} else {
+  process.stdin.resume()
+  process.stdin
+    .pipe(looseEnvify(__filename))
+    .pipe(process.stdout);
+}