be04c2854278ba29e35f5d1e038e8080f89975be
Seeds nisse-core as the home for system-level design documentation. The spec covers the shared library (Part A), both agents (Parts B and C), and the supporting services, build order, and open decisions. nisse-core holds this because the document describes the shared design rather than either agent's implementation; the repo gains code later, at the extraction step in the build order. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>