Add external GC1 consumer journey

[eamirian]

What changed

• add a frozen Market Intelligence cognition scenario and two-phase external GC1 verifier
• drive ACE only through the public ace cognition CLI; import no Core or ACE Python internals
• prove proposal, semantic diff, human approval, exact material use, restart persistence, exact later use, retirement, and fail-closed subsequent selection
• reject connection failures as false retirement evidence
• keep the verifier outside the inert Domain Pack wheel
• reconcile the already-public 0.6.0 release and GI2 status in the repository docs

Why

Core now has an obvious governed-cognition builder CLI, but GC1 requires an independent external consumer and a restart/failure-control journey. Market Intelligence is the first consumer because it exercises a real domain reasoning pattern without moving domain machinery into Core.

Boundary

This remains candidate evidence. GC1 does not pass until the Core CLI is published in a post-0.4.1 artifact and the same two-phase journey is rerun from exact public installations with retained receipts.

Verification

• exact CI posture: 131 passed, 1 intentional skip
• Ruff check and format check cover the new verifier and tests
• fresh root build retains exactly 39 JSON-only wheel resources; no script or executable code enters the Domain Pack