feat(wiki): add multimodal knowledge pipeline script

[MarinaMackay]

Summary

Part 4b of the multimodal repository knowledge stack.

This slice adds the end-to-end deterministic pipeline builder and local bundle build script.

Testing

python -m pytest test/scripts/test_build_multimodal_knowledge.py test/wiki/test_media_pipeline.py

[fishmingyu]

Thank you for the focused pipeline slice. I restacked the two original commits onto the merged upstream scorer work, preserved your authorship, and opened upstream PR sysevol-ai#671. The maintainer follow-up materializes generator exclusions across both scans, forwards custom scorers through the one-step builder, and adds repeatable CLI exclusions. Local verification: 409 passed.