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/syntax/node/Number.cjs

@@ -0,0 +1,25 @@
+'use strict';
+
+const types = require('../../tokenizer/types.cjs');
+
+const name = 'Number';
+const structure = {
+    value: String
+};
+
+function parse() {
+    return {
+        type: 'Number',
+        loc: this.getLocation(this.tokenStart, this.tokenEnd),
+        value: this.consume(types.Number)
+    };
+}
+
+function generate(node) {
+    this.token(types.Number, node.value);
+}
+
+exports.generate = generate;
+exports.name = name;
+exports.parse = parse;
+exports.structure = structure;