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/compat/math/sumBy.d.mts

@@ -0,0 +1,22 @@
+//#region src/compat/math/sumBy.d.ts
+/**
+ * Computes the sum of the values that are returned by the `iteratee` function.
+ *
+ * It does not coerce values to `number`.
+ *
+ * @template T - The type of the array elements.
+ * @param array - The array to iterate over.
+ * @param iteratee - The function invoked per iteration.
+ * @returns Returns the sum.
+ *
+ * @example
+ * sumBy([1, undefined, 2], value => value); // => 3
+ * sumBy(null); // => 0
+ * sumBy(undefined); // => 0
+ * sumBy([1, 2, 3]); // => 6
+ * sumBy([1n, 2n, 3n]); // => 6n
+ * sumBy([{ a: "1" }, { a: "2" }], object => object.a); // => "12"
+ */
+declare function sumBy<T>(array: ArrayLike<T> | null | undefined, iteratee?: ((value: T) => number) | string): number;
+//#endregion
+export { sumBy };