0.3.0 "Goshawk" — the interoperability release

Real Ed25519 signing (crypto extra) with did:key verification methods, verified cross-language by qg-rust. MCP server (querygraph mcp-serve), A2A Agent Card, OpenAI/Anthropic tool-schema export, async LangChain adapters, enriched OSI model (synonyms, relationships, dialect fallback), official OpenLineage 2-0-2 schema validation with spec-conformant deterministic UUIDv5 run ids, PyPI-ready packaging, GitHub Actions CI.

See CHANGELOG.md for full notes.