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/string/upperFirst.d.ts

@@ -0,0 +1,15 @@
+//#region src/string/upperFirst.d.ts
+/**
+ * Converts the first character of string to upper case.
+ *
+ * @param str - The string that is to be changed
+ * @returns The converted string.
+ *
+ * @example
+ * const convertedStr1 = upperFirst('fred') // returns 'Fred'
+ * const convertedStr2 = upperFirst('Fred') // returns 'Fred'
+ * const convertedStr3 = upperFirst('FRED') // returns 'FRED'
+ */
+declare function upperFirst(str: string): string;
+//#endregion
+export { upperFirst };