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/postcss-selector-parser/dist/util/index.js

@@ -0,0 +1,13 @@
+"use strict";
+
+exports.__esModule = true;
+exports.unesc = exports.stripComments = exports.getProp = exports.ensureObject = void 0;
+var _unesc = _interopRequireDefault(require("./unesc"));
+exports.unesc = _unesc["default"];
+var _getProp = _interopRequireDefault(require("./getProp"));
+exports.getProp = _getProp["default"];
+var _ensureObject = _interopRequireDefault(require("./ensureObject"));
+exports.ensureObject = _ensureObject["default"];
+var _stripComments = _interopRequireDefault(require("./stripComments"));
+exports.stripComments = _stripComments["default"];
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { "default": obj }; }