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/isBrowser.d.mts

@@ -0,0 +1,18 @@
+//#region src/predicate/isBrowser.d.ts
+/**
+ * Checks if the current environment is a browser.
+ *
+ * This function checks for the existence of the `window.document` property,
+ * which only exists in browser environments.
+ *
+ * @returns `true` if the current environment is a browser, otherwise `false`.
+ *
+ * @example
+ * if (isBrowser()) {
+ *   console.log("This is running in a browser");
+ *   document.getElementById('app').innerHTML = 'Hello World';
+ * }
+ */
+declare function isBrowser(): boolean;
+//#endregion
+export { isBrowser };