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/groupBy.d.ts

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+//#region src/array/groupBy.d.ts
+/**
+ * Groups the elements of an array based on a provided key-generating function.
+ *
+ * This function takes an array and a function that generates a key from each element. It returns
+ * an object where the keys are the generated keys and the values are arrays of elements that share
+ * the same key.
+ *
+ * @template T - The type of elements in the array.
+ * @template K - The type of keys.
+ * @param arr - The array to group.
+ * @param getKeyFromItem - A function that generates a key from an element, its index, and the array.
+ * @returns An object where each key is associated with an array of elements that
+ * share that key.
+ *
+ * @example
+ * const array = [
+ *   { category: 'fruit', name: 'apple' },
+ *   { category: 'fruit', name: 'banana' },
+ *   { category: 'vegetable', name: 'carrot' }
+ * ];
+ * const result = groupBy(array, item => item.category);
+ * // result will be:
+ * // {
+ * //   fruit: [
+ * //     { category: 'fruit', name: 'apple' },
+ * //     { category: 'fruit', name: 'banana' }
+ * //   ],
+ * //   vegetable: [
+ * //     { category: 'vegetable', name: 'carrot' }
+ * //   ]
+ * // }
+ *
+ * @example
+ * // Using index parameter
+ * const items = ['a', 'b', 'c', 'd'];
+ * const result = groupBy(items, (item, index) => index % 2 === 0 ? 'even' : 'odd');
+ * // result will be: { even: ['a', 'c'], odd: ['b', 'd'] }
+ */
+declare function groupBy<T, K extends PropertyKey>(arr: readonly T[], getKeyFromItem: (item: T, index: number, array: readonly T[]) => K): Record<K, T[]>;
+//#endregion
+export { groupBy };