feat: Support theme selector in HTML

[YueyingLu]

Issue #, if available:

Description of changes:

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.02% 🎉

Comparison is base (20ef6bf) 96.94% compared to head (5d38d0c) 96.96%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #59      +/-   ##
==========================================
+ Coverage   96.94%   96.96%   +0.02%     
==========================================
  Files          43       43              
  Lines        1016     1023       +7     
  Branches      119      121       +2     
==========================================
+ Hits          985      992       +7     
  Misses         29       29              
  Partials        2        2              

Files Changed	Coverage Δ
src/shared/declaration/rule.ts	100.00% <ø> (ø)
src/build/tasks/postcss/modules.ts	100.00% <100.00%> (ø)
src/shared/declaration/multi.ts	95.65% <100.00%> (ø)
src/shared/declaration/selector.ts	100.00% <100.00%> (ø)
src/shared/declaration/single.ts	100.00% <100.00%> (ø)
src/shared/styles/selector.ts	100.00% <100.00%> (ø)

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.