refactor: ontext managers for PDF

[gustavo-szesz]

Description

Brief description of the changes in this PR.

Related Issue

Fixes #(issue number)

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

Screenshots (if applicable)

Add screenshots to help explain your changes.

Additional Notes

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[NP-compete]

Thanks for the PR! 🎉

The lint check is failing because two files need formatting. Please run:

ruff format src/ tests/

This will reformat:

• src/pageindex/pdf/parser.py
• src/pageindex/utils.py

Then commit and push the changes. The CI should pass after that.

[NP-compete]

Closing pdf_reader.stream here will close the caller's BytesIO. They won't be able to reuse it after calling this function. Better to let the caller own the lifecycle.

[NP-compete]

This else branch is unreachable. The type hint is str | Path, so the isinstance check above always passes. Safe to remove.

[NP-compete]

The hasattr(pdf_reader, "stream") pattern relies on PyPDF2 internals. The with open() approach you used on lines 86-89 is cleaner. Consider using that consistently.