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/indent-string/index.js

@@ -0,0 +1,35 @@
+'use strict';
+
+module.exports = (string, count = 1, options) => {
+	options = {
+		indent: ' ',
+		includeEmptyLines: false,
+		...options
+	};
+
+	if (typeof string !== 'string') {
+		throw new TypeError(
+			`Expected \`input\` to be a \`string\`, got \`${typeof string}\``
+		);
+	}
+
+	if (typeof count !== 'number') {
+		throw new TypeError(
+			`Expected \`count\` to be a \`number\`, got \`${typeof count}\``
+		);
+	}
+
+	if (typeof options.indent !== 'string') {
+		throw new TypeError(
+			`Expected \`options.indent\` to be a \`string\`, got \`${typeof options.indent}\``
+		);
+	}
+
+	if (count === 0) {
+		return string;
+	}
+
+	const regex = options.includeEmptyLines ? /^/gm : /^(?!\s*$)/gm;
+
+	return string.replace(regex, options.indent.repeat(count));
+};