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/predicate/isUndefined.mjs

@@ -0,0 +1,26 @@
+//#region src/predicate/isUndefined.ts
+/**
+* Checks if the given value is undefined.
+*
+* This function tests whether the provided value is strictly equal to `undefined`.
+* It returns `true` if the value is `undefined`, and `false` otherwise.
+*
+* This function can also serve as a type predicate in TypeScript, narrowing the type of the argument to `undefined`.
+*
+* @param x - The value to test if it is undefined.
+* @returns true if the value is undefined, false otherwise.
+*
+* @example
+* const value1 = undefined;
+* const value2 = null;
+* const value3 = 42;
+*
+* console.log(isUndefined(value1)); // true
+* console.log(isUndefined(value2)); // false
+* console.log(isUndefined(value3)); // false
+*/
+function isUndefined(x) {
+	return x === void 0;
+}
+//#endregion
+export { isUndefined };