Document protocol compatibility and publish Hum 0.5.0

[delaudio]

Parent epic: #31

Goal

Ship the completed machine-readable integration protocol as a documented Hum release.

Dependencies

• Define versioned JSON success and error envelopes #34
• Add machine-readable project, template, and service discovery #32
• Add JSON output for service status #35
• Add JSON output for doctor diagnostics #33
• Add bounded JSON Lines output for logs and follow mode #36

Scope

• document every structured command and schema;
• state protocol compatibility and evolution rules;
• add end-to-end contract fixtures;
• publish Hum 0.5.0 through the existing release pipeline.

Acceptance criteria

• README or dedicated protocol documentation contains command examples and schemas.
• Compatibility rules distinguish CLI version from protocol schemaVersion.
• Additive versus breaking schema changes are defined.
• An integration can detect an unsupported Hum or schema version deterministically.
• End-to-end tests invoke the built binary and validate discovery, status, doctor, errors, and JSONL logs.
• Release notes call out the integration protocol.
• Release archives and Homebrew installation pass existing smoke tests.
• A v0.5.0 release is published.