harness: add Kilo Code CLI support

[willwashburn]

Summary

Add Kilo Code CLI as a Relay-supported coding harness.

Context

Kilo Code has a documented CLI surface for agentic coding. It should be evaluated separately from Cline because CLI flags, config, and extension points may differ.

Sources:

• https://kilo.ai/docs/code-with-ai/platforms/cli
• https://github.com/Kilo-Org/kilocode

Scope

• Add Kilo Code CLI metadata to the registry and generated outputs if feasible.
• Identify command flags for non-interactive/headless use.
• Investigate MCP/config integration for Relaycast.
• Add completion/readiness tests and docs.
• Compare implementation shape with Cline to avoid unnecessary duplication.

Acceptance

• Kilo Code has a documented Relay integration path or a clear no-go rationale.
• Supported modes include command-builder and smoke coverage.
• Docs include install, auth/provider setup, transport, and limitations.