spacedb-crdt 0.1.0

SpaceDB Layer 1 — convergent collections: the Y-CRDT (yrs) document model with a typed field->CRDT mapping (LWW-Register, PN-Counter, ...), local-first mutation, and order-independent merge. Phase 1 SpaceDB Mission, M2. See 'docs/plans/(working) phase 1 spacedb mission.md'.