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

Fix prompt template: bare {{ question }} since source question column has <image> baked in (avoid placeholder duplication)

Refine prompt_template_source: lmms-eval/VLMEvalKit canonical citations

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

Update metadata.json: add missing <image> placeholder to prompt_template

Add v2 manifest (metadata.json)