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/escape.d.mts

@@ -0,0 +1,17 @@
+//#region src/string/escape.d.ts
+/**
+ * Converts the characters "&", "<", ">", '"', and "'" in `str` to their corresponding HTML entities.
+ * For example, "<" becomes "&lt;".
+ *
+ * @param str  The string to escape.
+ * @returns Returns the escaped string.
+ *
+ * @example
+ * escape('This is a <div> element.'); // returns 'This is a &lt;div&gt; element.'
+ * escape('This is a "quote"'); // returns 'This is a &quot;quote&quot;'
+ * escape("This is a 'quote'"); // returns 'This is a &#39;quote&#39;'
+ * escape('This is a & symbol'); // returns 'This is a &amp; symbol'
+ */
+declare function escape(str: string): string;
+//#endregion
+export { escape };