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/function/once.js

@@ -0,0 +1,7 @@
+const require_once = require("../../function/once.js");
+//#region src/compat/function/once.ts
+function once(func) {
+	return require_once.once(func);
+}
+//#endregion
+exports.once = once;