v0.2.1 candidate — conditional sharp partial identification

Status: unrefereed candidate research release; not externally verified.

The mathematical claims are unchanged from v0.2.0. This publication-hardening release adds a pinned scratch-copy replay, citation and upstream-data audits, CC0-1.0 for original content, machine-readable assurance records, and DOI 10.5281/zenodo.21851319.

Internal gates: frozen package 22/22; normal scratch replay 20/20; optimized Python replay 20/20. These checks do not constitute peer review, formal proof verification, biological validation, exhaustive novelty, or independent reproduction.