feat: switch from tsup to tsdown

[JoshuaKGoldberg]

PR Checklist

• Addresses an existing open issue: fixes 🚀 Feature: Switch from tsup to tsdown #2223
• That issue was marked as status: accepting prs
• Steps in CONTRIBUTING.md were taken

Overview

Switches over, and includes intake/transition logic to remove the bundle property from old tsup.config.ts files.

Blocked from passing lint:spelling on streetsidesoftware/cspell-dicts#4518 -> #2237. ✅

🎁

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.80%. Comparing base (ac941e4) to head (66769f8).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2224   +/-   ##
=======================================
  Coverage   99.80%   99.80%           
=======================================
  Files         136      136           
  Lines        6099     6111   +12     
  Branches      505      509    +4     
=======================================
+ Hits         6087     6099   +12     
  Misses         12       12           

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[JoshuaKGoldberg]

🙌 thanks for the review @TheAlexLichter! Now that this is unblocked I'll apply the suggestions. They're really helpful.

[github-actions]

🎉 This is included in version v2.46.0 🎉

The release is available on:

• GitHub releases
• npm package (@latest dist-tag)

Cheers! 📦🚀

[johnnyreilly]

Nice! It looks like the switch from tsup to tsdown is pretty simple!

[TheAlexLichter]

Nice! It looks like the switch from tsup to tsdown is pretty simple!

That is one of the goals of tsdown - to be a "near" drop-in replacement (the few things that are different are listed in the migration guide)