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/array/flattenDepth.d.ts

@@ -0,0 +1,23 @@
+import { ListOfRecursiveArraysOrValues } from "../_internal/ListOfRecursiveArraysOrValues.js";
+
+//#region src/compat/array/flattenDepth.d.ts
+/**
+ * Recursively flattens array up to depth times.
+ *
+ * @template T
+ * @param array - The array to flatten.
+ * @param [depth=1] - The maximum recursion depth.
+ * @returns Returns the new flattened array.
+ *
+ * @example
+ * const array = [1, [2, [3, [4]], 5]];
+ *
+ * flattenDepth(array, 1);
+ * // => [1, 2, [3, [4]], 5]
+ *
+ * flattenDepth(array, 2);
+ * // => [1, 2, 3, [4], 5]
+ */
+declare function flattenDepth<T>(array: ListOfRecursiveArraysOrValues<T> | null | undefined, depth?: number): T[];
+//#endregion
+export { flattenDepth };