chore(config): single-source CLI/YAML help text on Field(description=)

[Vivian0108]

Closes #451.

[github-actions]

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (main@d3c57f2). Learn more about missing BASE report.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #535   +/-   ##
=======================================
  Coverage        ?   81.38%           
=======================================
  Files           ?      157           
  Lines           ?    22472           
  Branches        ?        0           
=======================================
  Hits            ?    18289           
  Misses          ?     4183           
  Partials        ?        0           

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[Vivian0108]

recheck