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/xor.d.ts

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+//#region src/array/xor.d.ts
+/**
+ * Computes the symmetric difference between two arrays. The symmetric difference is the set of elements
+ * which are in either of the arrays, but not in their intersection.
+ *
+ * @template T - The type of elements in the array.
+ * @param arr1 - The first array.
+ * @param arr2 - The second array.
+ * @returns An array containing the elements that are present in either `arr1` or `arr2` but not in both.
+ *
+ * @example
+ * // Returns [1, 2, 5, 6]
+ * xor([1, 2, 3, 4], [3, 4, 5, 6]);
+ *
+ * @example
+ * // Returns ['a', 'c']
+ * xor(['a', 'b'], ['b', 'c']);
+ */
+declare function xor<T>(arr1: readonly T[], arr2: readonly T[]): T[];
+//#endregion
+export { xor };