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/hacks/background-size.js

@@ -0,0 +1,23 @@
+let Declaration = require('../declaration')
+
+class BackgroundSize extends Declaration {
+  /**
+   * Duplication parameter for -webkit- browsers
+   */
+  set(decl, prefix) {
+    let value = decl.value.toLowerCase()
+    if (
+      prefix === '-webkit-' &&
+      !value.includes(' ') &&
+      value !== 'contain' &&
+      value !== 'cover'
+    ) {
+      decl.value = decl.value + ' ' + decl.value
+    }
+    return super.set(decl, prefix)
+  }
+}
+
+BackgroundSize.names = ['background-size']
+
+module.exports = BackgroundSize