chore: Fill in README and add tests for main.ts

[danvk]

This fills in usage for this repo (rather than the create-typescript-app template) and adds some tests for main.ts. I feel like there must be a more canonical way to mock the console methods for all tests in a group.

[github-actions]

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[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (d39a37d) 88.68% compared to head (b3a34f6) 94.70%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
src/main.ts	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #14      +/-   ##
==========================================
+ Coverage   88.68%   94.70%   +6.02%     
==========================================
  Files           9        9              
  Lines         716      718       +2     
  Branches       96      105       +9     
==========================================
+ Hits          635      680      +45     
+ Misses         80       37      -43     
  Partials        1        1              

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