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/array/flattenDeep.mjs

@@ -0,0 +1,18 @@
+import { flatten } from "./flatten.mjs";
+//#region src/array/flattenDeep.ts
+/**
+* Flattens all depths of a nested array.
+*
+* @template T - The type of elements within the array.
+* @param arr - The array to flatten.
+* @returns A new array that has been flattened.
+*
+* @example
+* const arr = flattenDeep([1, [2, [3]], [4, [5, 6]]]);
+* // Returns: [1, 2, 3, 4, 5, 6]
+*/
+function flattenDeep(arr) {
+	return flatten(arr, Infinity);
+}
+//#endregion
+export { flattenDeep };