Imp v0.3.1

Private source patch release. Clarifies the supported center versus pre-1.0 advanced workflows, documents the exact input/output typing contract and structured field schema, corrects the restricted-interpreter security boundary, and fixes cold-reader prerequisites and cross-references.\n\nPackage SHA-256: d3de6bfb6a4bc04993ba3ec415fa1937ed6a546c260e88c6d619fadf731458fa