Refactor API key handling in Streamlit logging

[coderabbitai]

The current implementation of API key handling in the Streamlit logging code has significant issues. Specifically, the TODO comments in the code highlight that API keys are initialized in random places, leading to potential security risks where one user's API keys could be accessed by another user.

To address this, the code needs to be refactored to:

1. Initialize API keys in a single place, preferably during the agent's initialization.
2. Allow unique API keys per registered user.

This refactor will ensure that API keys are handled securely and are unique to each user.

For more details, refer to the TODO comments in the following PR: #247 (comment)