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/predicate/isNaN.d.ts

@@ -0,0 +1,16 @@
+//#region src/compat/predicate/isNaN.d.ts
+/**
+ * Checks if the value is NaN.
+ *
+ * @param value - The value to check.
+ * @returns `true` if the value is NaN, `false` otherwise.
+ *
+ * @example
+ * isNaN(NaN); // true
+ * isNaN(0); // false
+ * isNaN('NaN'); // false
+ * isNaN(undefined); // false
+ */
+declare function isNaN(value?: any): boolean;
+//#endregion
+export { isNaN };