Decide the fate of the sequencing page now the backlog is one query

[sameera]

Decide whether docs/delivery/sequencing.md is reshaped, relocated onto issues, or retired, now that
the cross-feature backlog inventory it was hand-maintaining lives in one issue query.

Meta

• feature: docs/features/issue-sourced-planning
• estimate: S
• source: deferred from epic Backlog Stubs Become GitHub Issues (Backlog Stubs Become GitHub Issues #185) (2026-08-02)

The page existed largely because the 24 stubs were spread across 7 committed files with no
cross-feature view. Epic #185 replaced that inventory with gh issue list --state open --label backlog, and the page now carries a header line pointing at the query. What remains is wave ordering
and rationale — editorial judgement that the query does not express and that no issue field currently
holds. #185 declared deciding its fate explicitly out of scope: the migration should not retire a
page by side effect.

The options to weigh:

• Keep it, narrowed — the page becomes ordering-and-rationale only, with the inventory permanently
  delegated to the query. Cheapest; leaves one more hand-maintained surface whose issue numbers drift.
• Move the ordering onto the issues — express the waves as native blocked_by edges plus a
  milestone or project view, so ordering is derivable rather than transcribed. Consistent with the
  direction of Issue-Sourced Planning: Nothing Commits Until Close #114 and Backlog Stubs Become GitHub Issues #185; the rationale prose has no obvious home.
• Retire it — fold the surviving rationale into the affected stub bodies and delete the page.

Note that #185 already numbered every wave-table entry, so the transcription cost of keeping it is
now visible: each promotion or re-scope touches the page as well as the issue.