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/predicate/isFunction.js

@@ -0,0 +1,19 @@
+//#region src/predicate/isFunction.ts
+/**
+* Checks if `value` is a function.
+*
+* @param value The value to check.
+* @returns Returns `true` if `value` is a function, else `false`.
+*
+* @example
+* isFunction(Array.prototype.slice); // true
+* isFunction(async function () {}); // true
+* isFunction(function* () {}); // true
+* isFunction(Proxy); // true
+* isFunction(Int8Array); // true
+*/
+function isFunction(value) {
+	return typeof value === "function";
+}
+//#endregion
+exports.isFunction = isFunction;