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/util/attemptAsync.d.ts

@@ -0,0 +1,36 @@
+//#region src/util/attemptAsync.d.ts
+/**
+ * Attempt to execute an async function and return the result or error.
+ * Returns a Promise that resolves to a tuple where:
+ * - On success: [null, Result] - First element is null, second is the result
+ * - On error: [Error, null] - First element is the caught error, second is null
+ *
+ * @template {unknown} T - The type of the result of the async function.
+ * @template {unknown} E - The type of the error that can be thrown by the async function.
+ * @param func - The async function to execute.
+ * @returns A Promise that resolves to a tuple containing either [null, result] or [error, null].
+ *
+ * @example
+ * // Successful execution
+ * const [error, data] = await attemptAsync(async () => {
+ *   const response = await fetch('https://api.example.com/data');
+ *   return response.json();
+ * });
+ * // If successful: [null, { ... data ... }]
+ *
+ * // Failed execution
+ * const [error, data] = await attemptAsync(async () => {
+ *   throw new Error('Network error');
+ * });
+ * // [Error, null]
+ *
+ * // With type parameter
+ * const [error, users] = await attemptAsync<User[]>(async () => {
+ *   const response = await fetch('https://api.example.com/users');
+ *   return response.json();
+ * });
+ * // users is typed as User[]
+ */
+declare function attemptAsync<T, E>(func: () => Promise<T>): Promise<[null, T] | [E, null]>;
+//#endregion
+export { attemptAsync };