Add more file format tests (EPUB, RTF, CSV)

[kiyeonjeon21]

What

Add test cases for formats beyond PDF/DOCX that Kreuzberg supports.

How

1. Create sample fixtures in tests/conftest.py (small EPUB, RTF, CSV files)
2. Add tests in tests/test_parsers.py verifying Kreuzberg handles them
3. Run pytest -q to confirm

Files

• tests/conftest.py — add fixtures
• tests/test_parsers.py — add test cases

Context

Kreuzberg supports 91+ formats but we only test PDF, DOCX, XLSX, HTML, TXT. More coverage = more confidence.