modernize toolchain

[bartveneman]

• replace vite with tsdown
• add oxlint
• add oxfmt
• separate the CI jobs
• add dependabot
• update GH Actions versions

[codecov-commenter]

Bundle Report

Changes will increase total bundle size by 1.36kB (103.73%) ⬆️⚠️, exceeding the configured threshold of 5%.

Bundle name	Size	Change
cssTimeSort-esm	1.73kB	1.73kB (100%) ⬆️⚠️
formatCss-esm	(removed)	-367 bytes (-100.0%) ⬇️

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (bfcc834) to head (79758db).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #25   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines           47        47           
=========================================
  Hits            47        47           

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