Published branches: retire 73 integrated refs with owner approval #300

The branch owners should retire finished published working refs after confirming their remaining uses. The audit found 73 branch tips whose complete commit history is already contained in develop. Each has zero commits outside that exact canonical history. These refs sit outside the canonical lines and the current open PR head and target sets.

Snapshot: 8 October 2026, 17:09 UTC. GitHub listed 131 published branches and 21 open PRs. The audit checked exact commit ancestry and tree objects. develop was d430a133; main was 57eb7798.

This issue covers published GitHub refs. Existing product issues retain their implementation and acceptance work. Branch retirement requires the owner's agreement under AGENTS.md. Recheck the live head before acting on a row.

History containment makes these the first cleanup group. It does not establish product acceptance or settle deployment, release, fixture, or other active uses. In particular, the release-train refs and branches tied to open acceptance issues need those checks before retirement.

For each decision, record the live head, tree, branch owner, related issue or PR, and reason. Retained refs need a review or cleanup condition. Retirement needs owner agreement and an exact protecting GitHub ref, or an explicit decision to release unique history. A matching tree or adopted patch alone does not preserve the original commit history.

Completion criteria:

• Refresh every listed ref and confirm exact ancestry with git merge-base --is-ancestor <live-head> d430a1330e2b2e07afe0db3c13a13563b149ac3f, or repeat against the current canonical commit.
• Each branch owner records agreement to retire, or a retained role with its cleanup condition.
• Confirm PR relationships and any release, deployment, or artifact consumers before approved retirement.
• Complete approved remote retirements; record the removed head and date. Retained exceptions have an owner, reason, and condition.
• Refresh the published inventory and reconcile every row. Keep product acceptance open in its existing issue.

#122 owns project and PR record coherence. #50 records earlier integrated PR closures. This issue owns the published ref lifecycle and adds no release gate.

The full published audit covers 131 refs, with each ref listed in one group: #300 (73 integrated refs), #301 (7 legacy review refs), #302 (14 superseded candidates), #303 (9 research refs), #304 (28 canonical, active and context refs). Counts describe the snapshot above; refresh them when GitHub changes.