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.d.ts

@@ -0,0 +1,18 @@
+//#region src/function/once.d.ts
+/**
+ * Creates a function that is restricted to invoking func once. Repeat calls to the function return the value of the first invocation.
+ *
+ * @template F - The type of the function.
+ * @param func - The function to restrict.
+ * @returns Returns the new restricted function.
+ *
+ * @example
+ * const initialize = once(createApplication);
+ *
+ * initialize();
+ * initialize();
+ * // => `createApplication` is invoked once
+ */
+declare function once<F extends (...args: any[]) => any>(func: F): F;
+//#endregion
+export { once };