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/tailwindcss/lib/value-parser/walk.js

@@ -0,0 +1,16 @@
+"use strict";
+module.exports = function walk(nodes, cb, bubble) {
+    var i, max, node, result;
+    for(i = 0, max = nodes.length; i < max; i += 1){
+        node = nodes[i];
+        if (!bubble) {
+            result = cb(node, i, nodes);
+        }
+        if (result !== false && node.type === "function" && Array.isArray(node.nodes)) {
+            walk(node.nodes, cb, bubble);
+        }
+        if (bubble) {
+            cb(node, i, nodes);
+        }
+    }
+};