Merge PR #608: fix: remove unused imports and unnecessary f-strings

Authored by JackTheGit.

- Remove unused 'random' import from agent/display.py
- Remove unused 'Optional' import from agent/redact.py
- Remove unnecessary f-string prefixes in batch_runner.py

agent/display.py

@@ -6,7 +6,6 @@ Used by AIAgent._execute_tool_calls for CLI feedback.
 
 import json
 import os
-import random
 import sys
 import threading
 import time

agent/redact.py

@@ -10,7 +10,6 @@ the first 6 and last 4 characters for debuggability.
 import logging
 import os
 import re
-from typing import Optional
 
 logger = logging.getLogger(__name__)