litellm-0001: ProxyConfig._delete_deployment() checks model_id not in
combined_id_list (a plain Python list) for each router model ID during
config refresh. O(R*C) where R=router models, C=combined list. Fix:
convert to set before loop. MEDIUM severity, 6.5x at N=500. 1/1 PASS.
Haystack: no CWE-407 defects found. Uses dicts and sets throughout
for membership checks (scheduled_components set, storage dict, etc.).
