feat: add automatic tooltip repositioning for viewport overflow

[brianzhouzc]

Added logic that detects when tooltips would render outside the viewport and automatically flips/updates their position to maintain visibility.

Related: #7

[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 100.00%. Comparing base (ee8df97) to head (3a95fb5). :warning: Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #108   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines           80        94   +14     
=========================================
+ Hits            80        94   +14     

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

:rocket: New features to boost your workflow:

• :snowflake: Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[brianzhouzc]

Added test case for tooltip overflow.

I used the screeninfo package to get monitor information as it supports multiple platforms. AFAIK there's no reliable way to obtain monitor information natively with Tkinter.