SRV shape-space Fréchet radius and tangent-PCA effective dimension

Treats a whole protein (or its per-residue PLM representation) as a curve rather than a single pooled vector, maps it to the square-root-velocity (SRV) representation to quotient out rotations/translations, and then measures the resulting Riemannian shape space's Fréchet radius (spread) and tangent-PCA effective dimension (number of shape-variation degrees of freedom) — a curvature-aware generalization of [[intrinsic-dimension-estimation|TwoNN/effective-rank dimensionality profiling]] to whole-sequence shape rather than pointwise activation geometry.