feat: add collections validation and GFQL support

[lmeyerov]

Summary

• add collections validator with strict/autofix behavior and GFQL wire normalization
• expose collections API with validate/warn and plot-time URL param validation
• add collections tests and clarify plan template location
• move collections helpers to graphistry/collections.py and introduce typed models in graphistry/models/collections.py

Testing

• python -m pytest graphistry/tests/test_collections.py graphistry/tests/test_dataset_id_invalidation.py
• ./bin/lint.sh
• ./bin/mypy.sh