First public beta of the v2 protocol line. See CHANGELOG.md for
the full change list.

Triggers automatic publish to:
  • crates.io  (9 Rust crates, in topological order)
  • npm        (@aexproto/sdk, @aexproto/mcp-server via OIDC)
  • PyPI       (aex-sdk via OIDC)

Normative spec: docs/protocol-v2.md