FEAT: Added VLSU Multimodal Dataset

[riyosha]

Description

Added VLSU multimodal dataset. This dataset contains multimodal prompts (text+images) which have safety gradings and categories for the text, images and both combined. This functionality creates text prompts, image prompts and multimodal prompts from the same.

Closes #1285.

Files Changed:

pyrit/datasets/seed_datasets/remote/vlsu_multimodal_dataset.py (new)
pyrit/datasets/seed_datasets/remote/__init__.py (updated exports)
pyrit/datasets/__init__.py (updated exports)
tests/unit/datasets/test_vlsu_multimodal_dataset.py (new)
pyrit/models/seed.py (added optional prompt_text option in the image prompt)

Features:

• Loads image-text pairs from the official ML-VLSU repository
• Creates prompts based on safety grades:
  -- Text-only prompts: When text_grade is unsafe/borderline
  -- Image-only prompts: When image_grade is unsafe/borderline
  -- Combined prompts: When combined_grade is unsafe/borderline (captures emergent harm)
• Supports filtering by 15 harm categories (e.g., hate speech, discrimination, violence)
• Configurable unsafe_grades parameter to control which grades trigger prompt creation (options are safe, unsafe, borderline, not_sure)
• Supports random sampling with configurable limit and seed (for quicker testing. I can remove this if undesirable)
• Caches downloaded images locally for faster subsequent loads

Tests and Documentation

• Some essential unit tests added intests/unit/datasets/test_vlsu_multimodal_dataset.py
  -- Test dataset name property
  -- Test initialization with categories
  -- Test invalid categories raise ValueError
  -- Test text-only prompt creation (unsafe text grade)
  -- Test image-only prompt creation (unsafe image grade)
  -- Test combined prompt creation (unsafe combined grade)
  -- Test all prompts created when all grades unsafe
  -- Test borderline grades trigger prompt creation
  -- Test no prompts when all grades safe (expects error)
  -- Test category filtering
  -- Test handling of failed image downloads

• pre-commit run --all-files passes

[rlundeen2]

This is good! Thank you! I think once comments are addressed and CI passes it should be ready to merge.

[riyosha]

This is good! Thank you! I think once comments are addressed and CI passes it should be ready to merge.

I've made all the changes you mentioned, please lmk if you think any more changes are needed!