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/compat/array/join.mjs

@@ -0,0 +1,20 @@
+import { isArrayLike } from "../predicate/isArrayLike.mjs";
+//#region src/compat/array/join.ts
+/**
+* Joins elements of an array into a string.
+*
+* @param array - The array to join.
+* @param [separator=','] - The separator used to join the elements, default is common separator `,`.
+* @returns Returns a string containing all elements of the array joined by the specified separator.
+*
+* @example
+* const arr = ["a", "b", "c"];
+* const result = join(arr, "~");
+* console.log(result); // Output: "a~b~c"
+*/
+function join(array, separator) {
+	if (!isArrayLike(array)) return "";
+	return Array.from(array).join(separator);
+}
+//#endregion
+export { join };