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/workbox-range-requests/utils/parseRangeHeader.d.ts

@@ -0,0 +1,14 @@
+import '../_version.js';
+/**
+ * @param {string} rangeHeader A Range: header value.
+ * @return {Object} An object with `start` and `end` properties, reflecting
+ * the parsed value of the Range: header. If either the `start` or `end` are
+ * omitted, then `null` will be returned.
+ *
+ * @private
+ */
+declare function parseRangeHeader(rangeHeader: string): {
+    start?: number;
+    end?: number;
+};
+export { parseRangeHeader };