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-abstract/2022/IsStringPrefix.js

@@ -0,0 +1,19 @@
+'use strict';
+
+var $TypeError = require('es-errors/type');
+
+var StringIndexOf = require('./StringIndexOf');
+
+// https://262.ecma-international.org/13.0/#sec-isstringprefix
+
+module.exports = function IsStringPrefix(p, q) {
+	if (typeof p !== 'string') {
+		throw new $TypeError('Assertion failed: "p" must be a String');
+	}
+
+	if (typeof q !== 'string') {
+		throw new $TypeError('Assertion failed: "q" must be a String');
+	}
+
+	return StringIndexOf(q, p, 0) === 0;
+};