Add CI pipeline examples

[ahfoysal]

Summary:

• add ready-to-adapt GitHub Actions, GitLab CI, and Jenkins examples
• document where to find them and how to pass secrets, gating, and report paths

Checks:

• actionlint examples/github-actions.yml
• parsed GitHub Actions and GitLab YAML with Python
• ruby -c examples/jenkins/Jenkinsfile

Closes #49

[advaitpatel]

@ahfoysal this looks good. I will take a look at it in some time.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (main@b62a7d7). Learn more about missing BASE report.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #142   +/-   ##
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  Coverage        ?   79.26%           
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  Files           ?       30           
  Lines           ?     4557           
  Branches        ?        0           
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  Hits            ?     3612           
  Misses          ?      945           
  Partials        ?        0           

Flag	Coverage Δ
unittests	79.26% <ø> (?)

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