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/lodash/floor.js

@@ -0,0 +1,26 @@
+var createRound = require('./_createRound');
+
+/**
+ * Computes `number` rounded down to `precision`.
+ *
+ * @static
+ * @memberOf _
+ * @since 3.10.0
+ * @category Math
+ * @param {number} number The number to round down.
+ * @param {number} [precision=0] The precision to round down to.
+ * @returns {number} Returns the rounded down number.
+ * @example
+ *
+ * _.floor(4.006);
+ * // => 4
+ *
+ * _.floor(0.046, 2);
+ * // => 0.04
+ *
+ * _.floor(4060, -2);
+ * // => 4000
+ */
+var floor = createRound('floor');
+
+module.exports = floor;