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/tiny-invariant/dist/esm/tiny-invariant.d.ts

@@ -0,0 +1,21 @@
+/**
+ * `invariant` is used to [assert](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html#assertion-functions) that the `condition` is [truthy](https://github.com/getify/You-Dont-Know-JS/blob/bdbe570600d4e1107d0b131787903ca1c9ec8140/up%20%26%20going/ch2.md#truthy--falsy).
+ *
+ * 💥 `invariant` will `throw` an `Error` if the `condition` is [falsey](https://github.com/getify/You-Dont-Know-JS/blob/bdbe570600d4e1107d0b131787903ca1c9ec8140/up%20%26%20going/ch2.md#truthy--falsy)
+ *
+ * 🤏 `message`s are not displayed in production environments to help keep bundles small
+ *
+ * @example
+ *
+ * ```ts
+ * const value: Person | null = { name: 'Alex' };
+ * invariant(value, 'Expected value to be a person');
+ * // type of `value`` has been narrowed to `Person`
+ * ```
+ */
+export default function invariant(condition: any, 
+/**
+ * Can provide a string, or a function that returns a string for cases where
+ * the message takes a fair amount of effort to compute
+ */
+message?: string | (() => string)): asserts condition;