[scanner] ADR 0025 (central stage engine) not synced or in nav — hive v5 docs drift #417

Summary

hivecommons/hive@v5 added src/docs/adr/0025-central-stage-engine.md (landed 2026-10-20), but the docs site does not publish it:

• scripts/sync-hive-docs.ts files[] stops at adr/0024-provider-credential-lifecycle.md (line 84), so the prebuild sync never fetches ADR 0025.
• src/app/docs/page-map.ts NAV_STRUCTURE_HIVE → Reference → "Architecture Decision Records" stops at 0024 Provider credential lifecycle (line 182), so even if synced it would not appear in the sidebar.

Effect

• /docs/hive/reference/architecture-decision-records/0025-central-stage-engine does not exist on the site.
• The synced ADR index (adr/readme.md) links 0025-central-stage-engine.md relatively; because the target is not a synced page, scripts/link-rewrite.ts rewrites it to a github.com/.../blob/v5/... URL, so readers are bounced off the docs site for that one ADR while 0001–0024 stay on-site.

Evidence

• gh api repos/hivecommons/hive/contents/src/docs/adr?ref=v5 lists 0025-central-stage-engine.md.
• grep -n 0025 scripts/sync-hive-docs.ts src/app/docs/page-map.ts → no matches.
• Prior instance of the same drift: [quality] hive sidebar misses ADRs 0018–0024 synced in #360 — add nav entries and a sync↔nav drift guard #389 / fix(nav): list ADRs 0018-0024 in the hive sidebar and guard sync/nav drift #390 (ADRs 0018–0024 added the same way).

Fix

Add { source: "adr/0025-central-stage-engine.md" } to scripts/sync-hive-docs.ts and { '0025 Central stage engine': 'adr/0025-central-stage-engine.md' } to the ADR nav in src/app/docs/page-map.ts (matching the existing pattern for 0018–0024 in #390). The repo's existing nav/page-map tests cover routing.

This is the second time the ADR list has drifted from hive; if it recurs a follow-up could make the sync enumerate adr/*.md from the hive tree instead of a hardcoded list.

— hive: agent=scanner backend=copilot model=claude-fable-5.1 copilot=1.0.88