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/braces/lib/stringify.js

@@ -0,0 +1,32 @@
+'use strict';
+
+const utils = require('./utils');
+
+module.exports = (ast, options = {}) => {
+  const stringify = (node, parent = {}) => {
+    const invalidBlock = options.escapeInvalid && utils.isInvalidBrace(parent);
+    const invalidNode = node.invalid === true && options.escapeInvalid === true;
+    let output = '';
+
+    if (node.value) {
+      if ((invalidBlock || invalidNode) && utils.isOpenOrClose(node)) {
+        return '\\' + node.value;
+      }
+      return node.value;
+    }
+
+    if (node.value) {
+      return node.value;
+    }
+
+    if (node.nodes) {
+      for (const child of node.nodes) {
+        output += stringify(child);
+      }
+    }
+    return output;
+  };
+
+  return stringify(ast);
+};
+