feat(tui): improve the white theme support

[orhun]

Description of change

Now we check the background color of the terminal and use a more fitting color for text. (e.g. white text on a black background)

Closes #8

How has this been tested? (if applicable)

Locally, with different themes.

[orhun]

100ms timeout seems a bit high - I need to make it run in a thread via message passing.

[orhun]

Found another library which might be more suitable for this: https://github.com/Canop/terminal-light

[orhun]

100ms timeout seems a bit high - I need to make it run in a thread via message passing.

Turns out this is not going to work since we can't query the terminal background color correctly while the terminal events are being read at the same time.

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 0% with 106 lines in your changes missing coverage. Please review.

Project coverage is 3.55%. Comparing base (29d88dc) to head (52f7ced).

Files with missing lines	Patch %	Lines
src/tui/ui.rs	0.00%	99 Missing ⚠️
src/tui/state.rs	0.00%	7 Missing ⚠️

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Additional details and impacted files

@@           Coverage Diff            @@
##            main     #23      +/-   ##
========================================
- Coverage   3.67%   3.55%   -0.11%     
========================================
  Files         18      18              
  Lines       2212    2286      +74     
========================================
  Hits          81      81              
- Misses      2131    2205      +74     

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