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/fp/math/add.d.ts

@@ -0,0 +1,17 @@
+//#region src/fp/math/add.d.ts
+/**
+ * Creates a function that adds `addend` to its input. Use it with {@link pipe},
+ * or as the callback of a function such as {@link map}.
+ *
+ * @param addend - The number to add to the input.
+ * @returns A function that maps a `number` to `value + addend`.
+ *
+ * @example
+ * import { pipe, map, add } from 'es-toolkit/fp';
+ *
+ * pipe(3, add(2)); // => 5
+ * pipe([1, 2, 3], map(add(10))); // => [11, 12, 13]
+ */
+declare function add(addend: number): (value: number) => number;
+//#endregion
+export { add };