metadata: add score_type/score_params/score_protocol (official grading protocol taxonomy); task_type is now format-only (judge_scored migrated to vqa + llm_judge). See dataset-upload skill references/metadata-json.md.

Tighten prompt_template_source.notes: explicit 5-tier classification per 2026-06-01 priority rules

Populate prompt_template_source for all subsets per 2026-05-30 audit

Update metadata.json: Apply 2026-05-19 audit template fix

Add v2 manifest (metadata.json)