ReplicaSurety — minimal reference implementation

This repository provides a focused implementation of core ReplicaSurety primitives:

- PoeticCert and ReplayBundle JSON schemas (Pydantic models)
- A tiny off-chain Surety Ledger FastAPI service with basic escrow lifecycle endpoints
- A deterministic ReplayBundle verifier (reference behavior)
- Tests and packaging metadata so `bash test.sh` runs pytest and builds the package

This is intentionally minimal and meant as a starting point for the community PoC.