fix(youtube): support playlist video type filter

[merlinsantiago982-cmd]

Summary

• add the playlist videos type filter to match channel videos
• avoid sending Python's built-in type object as a query param
• normalize videoIds/shortIds/liveIds and snake_case responses into VideoIds
• document playlist type usage and add regression coverage

Validation

• .venv-codex/bin/python -m pytest tests/test_client.py -q
• .venv-codex/bin/python -m py_compile supadata/youtube.py tests/test_client.py

Fixes #12
/claim #12