fix: disable callback tracing in Streamlit UI runs by default

[DavidJBianco]

Motivation

• Prevent routine Streamlit UI interactions from enabling agent callback file logging that persists prompt/response content to disk (msgs.txt / results.txt), which creates an information exposure and disk-growth risk.

Description

• Updated the Streamlit UI runner calls to invoke the agent runner with debug_agents=False instead of True in peak_assistant/streamlit/util/ui.py, preventing default injection of preprocess_messages_logging/postprocess_messages_logging callbacks while preserving agent behavior.

Testing

• Ran unit test collection with pytest and it failed during collection due to a missing dependency (ModuleNotFoundError: No module named 'dotenv'), so no tests specific to this change could be executed in this environment.

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Codex Task

[DavidJBianco]

Superseded by #87. The fix was applied as a default change in peak_assistant_chat() (debug_agents: bool = True → False) rather than hardcoding False at call sites, since the main branch had already threaded the parameter through. Merged into dev.