ui : drop a stray doc comment over the hidden models loader

The comment described a timestamp helper that moved away earlier.

Assisted-by: pi (zai-org/GLM-5.3-Flash)

tools/ui/src/lib/stores/models/index.svelte.ts

@@ -52,7 +52,6 @@ function mergedDraftSidecars(
 	return merged;
 }
 
-/** Last use timestamp per backend-qualified model id. */
 /** Models kept out of the selector. */
 function loadHiddenModels(): Set<string> {
 	if (!browser) return new SvelteSet<string>();