ui: drop "Visited Sources" appendix from final answer

Inline answer is cleaner without the trailing URL list — citations the
model chose to embed inside the answer remain, and the full visited-URL
log is still in the Record (trace JSON) tab for anyone who needs it.

app.py

@@ -2288,10 +2288,7 @@ def build_research_agent(
     else:
         final_answer = ensure_markdown_table_blank_lines(final_answer)
 
-    citations = "\n".join(f"- {url}" for url in sorted(set(state.visited_urls)))
     final_answer = f"**Model used:** `{used_model}`\n\n{final_answer}"
-    if citations:
-        final_answer = f"{final_answer}\n\n### Visited Sources\n{citations}"
 
     trace_text = _trace_to_json(state, used_model)
     yield (final_answer, trace_text)