v6.3.0: Agent Automation Parity

[flyingrobots]

Outcome

The machine-facing git cas agent surface reaches parity for the workflows agents need without scraping human CLI output or TUI state.

Scope

• Inventory agent command parity against human workflows.
• Stabilize JSON result shapes and error contracts where drift exists.
• Add automation examples and lower-mode witnesses.

Required Proof

• Agent command behavior tests.
• Machine-readable witness output for changed contracts.