Demote to pointer: canonical is csoai/gspc-prv

point to canonical csoai/gspc-prv

fix: pin configs so datasets-server loads (was CastError on multi-schema glob)

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card: regenerate from measured data — single H1, correct n, measured difficulty/spread/usable_n, and the honest limit that this axis is not yet quotable

A+++ AEO/branded card: GSPC family cross-links, keyword frontmatter

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initial commit