UI.17 Stability pass: every app × every layout × both themes × three widths on one contact sheet, the engine gaps closed, tests that hold

Owner: "I personally dont feel like our efforts are strong and stable and consistent." What exists: bin/test-app-workspaces.mjs (12 contract points per app and layout, green on 2026-10-24 for the two layouts of that day); the newer layouts were checked in CadCraft and BimCraft only (DU.1, VEC.1, SK.1 all "partial"); the engine inbox (docs/0.7-sessions/workspace-layouts.md § Inbox) lists gaps the per-app sessions found, most closed in the follow-up run, some still worked around in app CSS (z-index lifts, canvas sizing); FX.37 (tablets in portrait), FX.43 (packaged editions print no mount for toolbar tear) and FX.82 to FX.85 are partial. This row: (1) a contact sheet tool (tools/workspace-test/contact-sheet.mjs) that opens every app (eight plus SuperCad) in every layout, light and dark, at 1920, 1280 and 760 px wide with a showcase file, and writes one page of screenshots for the owner, re-run before every release and kept in the release notes results section; (2) run the conformance test for every app × layout and fix what fails, including the new points from UI.1; (3) remove the per-app CSS workarounds the engine now covers; (4) the partial rows above closed or re-filed; (5) a flake budget: the suite runs three times green on the VPS before this row is Built.