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/unionBy.mjs

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+import { uniqBy } from "./uniqBy.mjs";
+//#region src/array/unionBy.ts
+/**
+* Creates an array of unique values, in order, from all given arrays using a provided mapping function to determine equality.
+*
+* @template T - The type of elements in the array.
+* @template U - The type of mapped elements.
+* @param arr1 - The first array.
+* @param arr2 - The second array.
+* @param mapper - The function to map array elements to comparison values.
+* @returns A new array containing the union of unique elements from `arr1` and `arr2`, based on the values returned by the mapping function.
+*
+* @example
+* // Custom mapping function for numbers (modulo comparison)
+* const moduloMapper = (x) => x % 3;
+* unionBy([1, 2, 3], [4, 5, 6], moduloMapper);
+* // Returns [1, 2, 3]
+*
+* @example
+* // Custom mapping function for objects with an 'id' property
+* const idMapper = (obj) => obj.id;
+* unionBy([{ id: 1 }, { id: 2 }], [{ id: 2 }, { id: 3 }], idMapper);
+* // Returns [{ id: 1 }, { id: 2 }, { id: 3 }]
+*/
+function unionBy(arr1, arr2, mapper) {
+	return uniqBy(arr1.concat(arr2), mapper);
+}
+//#endregion
+export { unionBy };