fix: resolve ruff lint and format errors across codebase

Fix E402 import ordering, F841 unused variable, F541 unnecessary
f-strings, F401 unused import, and auto-format 6 files.

benchmarks/convomem_bench.py

@@ -25,20 +25,19 @@ import os
 import sys
 import json
 import shutil
+import ssl
 import tempfile
 import argparse
 import urllib.request
-import ssl
-
-# Bypass SSL for restricted environments
-ssl._create_default_https_context = ssl._create_unverified_context
-
 from pathlib import Path
 from collections import defaultdict
 from datetime import datetime
 
 import chromadb
 
+# Bypass SSL for restricted environments
+ssl._create_default_https_context = ssl._create_unverified_context
+
 sys.path.insert(0, str(Path(__file__).parent.parent))
 
 HF_BASE = "https://huggingface.co/datasets/Salesforce/ConvoMem/resolve/main/core_benchmark/evidence_questions"