Fix repeated PDF.js vendor check failures

[ZHINFINITY]

Summary

• use the workspace-local PostCSS CLI for PDF.js vendor flattening
• write output through PostCSS explicitly instead of shell redirection
• keep scheduled Nightly and Android E2E vendor setup deterministic

This addresses the repeated Input Error: You must pass a valid list of files to parse failures in the scheduled checks.

Summary by CodeRabbit

• Chores
  • Updated PDF.js styling build commands for more consistent CSS processing.
  • Preserved nested CSS support and flattened output generation.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Team

Run ID: 4abdfc2d-22c0-4cc1-bdb3-400c14db2caa

📥 Commits

Reviewing files that changed from the base of the PR and between 48a2b9a and fb76d0b.

📒 Files selected for processing (1)

• apps/readest-app/package.json

Included review availability: Your plan provides up to 8 included reviews per hour; 7 remain after this review.

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📝 Walkthrough

Walkthrough

The PDF.js annotation-layer and text-layer CSS-copy scripts now invoke the project-local PostCSS executable through pnpm exec. Nested CSS processing and flattened output generation remain unchanged.

Changes

PDF.js CSS build scripts

Layer / File(s)	Summary
Update PostCSS script invocation apps/readest-app/package.json	The annotation-layer and text-layer CSS-copy scripts now use pnpm exec postcss. Their existing options and outputs remain unchanged.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Merge Risk: ⚪ Minimal · up to fb76d

This localized CI configuration change is merge-ready after normal checks and review; no actionable merge-blocking risk remains.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the main change: fixing repeated PDF.js vendor check failures. It is concise and specific.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0 files. (1 skipped: 1 unsupported.)

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/ci-pdfjs-postcss

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