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/strip-indent/index.d.ts

@@ -0,0 +1,21 @@
+/**
+Strip leading whitespace from each line in a string.
+
+The line with the least number of leading whitespace, ignoring empty lines, determines the number to remove.
+
+@example
+```
+import stripIndent = require('strip-indent');
+
+const string = '\tunicorn\n\t\tcake';
+//	unicorn
+//		cake
+
+stripIndent(string);
+//unicorn
+//	cake
+```
+*/
+declare function stripIndent(string: string): string;
+
+export = stripIndent;