integration: research GitHub Copilot agent/CLI lifecycle support

[SignalLayerLabs]

Context

GitHub Copilot is still listed as roadmap work in MARGINAL's integration overview.

Goal

Determine which currently supported Copilot surface, if any, can provide stable action lifecycle events for an Observe-first adapter.

Acceptance criteria for the research phase

• Name the exact product surface and tested version.
• Use official integration/lifecycle mechanisms where available.
• Separate observable facts from inferred outcomes.
• Do not claim Tool or Full Compute Enforcement without a real interception boundary.
• Map the smallest viable adapter onto the Universal Agent Protocol.
• Document uninstall/fail-open behavior and privacy implications.

Implementation should follow only if the lifecycle surface is defensible.