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/css-tree/lib/syntax/node/String.js

@@ -0,0 +1,19 @@
+import { String as StringToken } from '../../tokenizer/index.js';
+import { decode, encode } from '../../utils/string.js';
+
+export const name = 'String';
+export const structure = {
+    value: String
+};
+
+export function parse() {
+    return {
+        type: 'String',
+        loc: this.getLocation(this.tokenStart, this.tokenEnd),
+        value: decode(this.consume(StringToken))
+    };
+}
+
+export function generate(node) {
+    this.token(StringToken, encode(node.value));
+}