app/views/articles/show.html.erb now tabs the main content column via the tabs Stimulus controller: an “Overview” tab (article content) and an owner-only “DM Notes” tab (with the lock icon), replacing the red-bordered box that sat at the bottom of the article body. Both tab button and panel are rendered together inside the policy(@article).update? && dm_notes.present? branch so indices stay aligned; non-owners and notes-less articles fall through to the plain content render (no pointless single-tab bar). Gallery right-panel and player view untouched. No model or MCP change (dm_notes already existed). Seed parity: Marta Vance seeded with dm_notes to exercise the tab. Verified in-browser as the DM (tab toggles, secrets hidden from the overview).
BL-053
Shipped