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/@babel/code-frame/README.md

@@ -0,0 +1,19 @@
+# @babel/code-frame
+
+> Generate errors that contain a code frame that point to source locations.
+
+See our website [@babel/code-frame](https://babeljs.io/docs/babel-code-frame) for more information.
+
+## Install
+
+Using npm:
+
+```sh
+npm install --save-dev @babel/code-frame
+```
+
+or using yarn:
+
+```sh
+yarn add @babel/code-frame --dev
+```