Revert "revert: roll back v12.3.3 (Issue Blowout 2026)"

This reverts commit bfc7de377a.

src/ui/viewer/utils/api.ts

@@ -0,0 +1,7 @@
+/**
+ * Fetch wrapper for viewer API calls.
+ * Worker is localhost-only; no auth header needed.
+ */
+export function authFetch(input: RequestInfo | URL, init?: RequestInit): Promise<Response> {
+  return fetch(input, init);
+}