Add settings page for managing forecasting API key and URL via UI

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/node_modules/es-toolkit/dist/fp/array/length.d.mts

@@ -0,0 +1,18 @@
+//#region src/fp/array/length.d.ts
+/**
+ * Creates a function that returns the length of an array.
+ *
+ * Use it with {@link pipe} when a pipeline should end with the number of input values.
+ *
+ * @template T - The type of elements in the array.
+ * @returns A function that maps a readonly array to its length.
+ *
+ * @example
+ * import { length, pipe } from 'es-toolkit/fp';
+ *
+ * pipe(['a', 'b', 'c'], length());
+ * // => 3
+ */
+declare function length<T>(): (array: readonly T[]) => number;
+//#endregion
+export { length };