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/index.js

@@ -0,0 +1,10 @@
+import createSyntax from './create.js';
+import lexerConfig from './config/lexer.js';
+import parserConfig from './config/parser.js';
+import walkerConfig from './config/walker.js';
+
+export default createSyntax({
+    ...lexerConfig,
+    ...parserConfig,
+    ...walkerConfig
+});