v0.14.0

Security

• Made the first-party Action execute the source selected by its reference with the committed
  uv.lock, a pinned setup-uv revision, and an explicit uv version. The contract path crosses
  the composite Action boundary through an environment variable and remains a quoted argument
  rather than shell input. An option terminator prevents option-like filenames from changing CLI
  behavior.
• Kept CI evidence opt-in. The Action neither uploads response data nor requests write
  permissions, leaving potentially sensitive artifacts under the caller's explicit control.

Features

• Added a root composite GitHub Action that runs a2a-proof.yaml as a behavioral CI check. Its
  single optional config input selects a non-default contract; advanced controls remain in the
  CLI.
• Added a2a-proof demo, which starts a deterministic loopback agent and performs an A2A JSON-RPC
  exchange without keys or an external service. It checks state, structured data, file size, and
  SHA-256; --fail demonstrates diagnostics and exit code 1.

Documentation

• Added the local demo and minimal Action invocation to the README, while keeping complete
  workflow, security, evidence, and advanced-option guidance in the operations guide.

Maintenance

• Added a CI consumer for the repository's own Action. It starts the demo agent on an ephemeral
  port and runs the environment-backed contract through the locked Action runtime.
• Added CLI and live protocol coverage for both successful and intentionally failing demo paths.
• Established a clean core mutation baseline: 4,405 of 4,579 mutants are killed (96.20%). Four
  timeouts remain in the bounded push wait, listener, and socket-read mutations; all other abnormal
  statuses are zero. The threaded demo agent stays under live and negative protocol tests because
  mutating its request handlers destabilizes the in-process mutation collector.