Adds SummaryTracker class and implements basic timer.

[jkcchan]

#183

This pull request introduces a new SummaryTracker class to track and summarize execution time for the core function.

• This timer starts after authentication to avoid bloated time due to user input.
• Made in a way to extend to more summary metrics.

The changes include integrating the SummaryTracker into the core function, adding a timer mechanism, and creating unit tests to validate its functionality.

[jkcchan]

note to self: i should use the logger class. oops.