Components: Add popup-family transactions and owner-relative focus restoration #4377

Goal

Implement the shared native policy needed beyond a flat nonmodal Callout/Menu composition. Part of #4274. Actual Menu and Popover delivery remains #4232 and #4236; do not duplicate those component-generation issues.

Observed baseline — 2026-10-15

The initial native-core milestone confirms individual presentation focus/close/reposition and owner-window retained-focus return. It does not provide family closure, policy-driven restoration, natural owner-relative Tab continuation, request-only veto, or precise light-dismiss classification. The MenuComposition story is a prerequisite demonstration, not a shipped Menu/Popover component.

Acceptance

• Review the shared contract for family membership/attachment generations, child/sibling/ancestor closure, reentrant dismissal, and stale result/cleanup fencing.
• Implement family-close/restoration transactions with one navigation owner per key and one native restoration executor. Test close/reopen, owner loss, nested popup input, Escape, and restoration races.
• Provide natural owner-relative Tab/Shift+Tab continuation without cycling back into closing popups or restoring over a newer physical focus move.
• Resolve disabled-but-discoverable MenuItem policy: focus eligibility, activation refusal, and accessibility-disabled state are separate axes. Integrate the reviewed choice with Components: Generate Menu #4232 rather than silently changing all disabled controls.
• Keep pointer-open focus policy explicit (platform / always / never) and retain the flat default/always trigger-restoration regressions on all qualified hosts.
• Record macOS Paper/Fabric and Windows/Win32 capability evidence and unsupported paths; do not claim root admission from a partial host implementation.

Prior art and evidence

Historical handoff: b55d6c9a3:packages/agentic/native-core/plans/modernization.md. Candidate wave-three 5f6e7af1252bcfe087dcd1672afaa4ceb7c5efbb contains macOS family work but narrower RNW coverage and a recorded Menu run of 1 passed / 0 failed / 12 skipped. Adapt selectively under current native/Apple contracts, not as already-qualified behavior. Preserve renderer adapters as thin event/view boundaries and shared behavior independent of renderer registries.