[SDUI][P0] RuntimeDraftBar for record pages & forms #1542

Context

Dashboards and reports show an "unpublished changes" bar with Publish/Discard. Record pages and forms have no such affordance, so runtime page edits (once persisted, see the page-persistence issue) have no publish UI.

Goal

A reusable RuntimeDraftBar surfaced on record pages (and forms) that indicates an unpublished draft exists and offers Publish / Discard, wired to the ADR-0034 seam.

Scope

• Extract/reuse the dashboard/report draft-bar pattern into a shared component.
• Mount it on RecordDetailView (and RecordFormPage) when readRuntimeDraft returns a draft.
• Publish → publishRuntimeMetadata; Discard → discardRuntimeMetadata; both refresh the rendered schema.

Acceptance

• Bar appears only when an unpublished draft exists for the current page/form
• Publish/Discard call the seam and update the view without a full reload
• Live e2e covers appear → publish → disappear