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/cjs/lexer/generic-const.cjs

@@ -0,0 +1,12 @@
+'use strict';
+
+// https://drafts.csswg.org/css-cascade-5/
+const cssWideKeywords = [
+    'initial',
+    'inherit',
+    'unset',
+    'revert',
+    'revert-layer'
+];
+
+exports.cssWideKeywords = cssWideKeywords;