Establishes glas-harness as the framework routing between concrete
harness backends ("reins"): rein-aharness (renamed from agent-harness)
and the newly chartered rein-openweights. GLAS-WP-0001 defines the
harness contract, rein registry, and a minimal gateway proving parity
against rein-aharness.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>