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/Hash.js

@@ -0,0 +1,23 @@
+import { Hash } from '../../tokenizer/index.js';
+
+// '#' ident
+export const xxx = 'XXX';
+export const name = 'Hash';
+export const structure = {
+    value: String
+};
+export function parse() {
+    const start = this.tokenStart;
+
+    this.eat(Hash);
+
+    return {
+        type: 'Hash',
+        loc: this.getLocation(start, this.tokenStart),
+        value: this.substrToCursor(start + 1)
+    };
+}
+export function generate(node) {
+    this.token(Hash, '#' + node.value);
+}
+