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/function/once.mjs

@@ -0,0 +1,31 @@
+//#region src/function/once.ts
+/**
+* Creates a function that is restricted to invoking the provided function `func` once.
+* Repeated calls to the function will return the value from the first invocation.
+*
+* @template F - The type of function.
+* @param func - The function to restrict.
+* @returns A new function that invokes `func` once and caches the result.
+*
+* @example
+* const initialize = once(() => {
+*   console.log('Initialized!');
+*   return true;
+* });
+*
+* initialize(); // Logs: 'Initialized!' and returns true
+* initialize(); // Returns true without logging
+*/
+function once(func) {
+	let called = false;
+	let cache;
+	return function(...args) {
+		if (!called) {
+			called = true;
+			cache = func(...args);
+		}
+		return cache;
+	};
+}
+//#endregion
+export { once };