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/isLength.d.mts

@@ -0,0 +1,25 @@
+//#region src/compat/predicate/isLength.d.ts
+/**
+ * Checks if a given value is a valid length.
+ *
+ * A valid length is of type `number`, is a non-negative integer, and is less than or equal to
+ * JavaScript's maximum safe integer (`Number.MAX_SAFE_INTEGER`).
+ * It returns `true` if the value is a valid length, and `false` otherwise.
+ *
+ * This function can also serve as a type predicate in TypeScript, narrowing the type of the
+ * argument to a valid length (`number`).
+ *
+ * @param value The value to check.
+ * @returns Returns `true` if `value` is a valid length, else `false`.
+ *
+ * @example
+ * isLength(0); // true
+ * isLength(42); // true
+ * isLength(-1); // false
+ * isLength(1.5); // false
+ * isLength(Number.MAX_SAFE_INTEGER); // true
+ * isLength(Number.MAX_SAFE_INTEGER + 1); // false
+ */
+declare function isLength(value?: any): boolean;
+//#endregion
+export { isLength };