ci: Approve pnpm build scripts for docs build

[vdusek]

The recent bump to pnpm v11 (#841) turned ignored package build scripts into a hard error, breaking the docs check:

[ERR_PNPM_IGNORED_BUILDS] Ignored build scripts: @apify/ui-icons, @swc/core, core-js, unrs-resolver

This explicitly approves those packages' build scripts via an allowBuilds section in website/pnpm-workspace.yaml (pnpm 11's mechanism for opting dependencies into running install scripts).

Verified locally that pnpm install and uv run poe build-docs both succeed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.72%. Comparing base (beab127) to head (b9e707a).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master     #842       +/-   ##
===========================================
+ Coverage   83.52%   94.72%   +11.19%     
===========================================
  Files          48       48               
  Lines        5045     5045               
===========================================
+ Hits         4214     4779      +565     
+ Misses        831      266      -565     

Flag	Coverage Δ
integration	92.84% <ø> (?)
unit	83.52% <ø> (ø)

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[vdusek]

@B4nan, could you please check it? If this is the right way, I'll do it in the SDK & Crawlee as well.

[B4nan]

lets drop core-js, otherwise it looks good.