Quiet fields: base.css field baseline, --field tokens, 3:1 border-strong, app-wide migration

docs/ux-second-pass.md

@@ -8,22 +8,6 @@ record the resolution into the contract (`docs/architecture/09`+`10` and the rel
 
 ## Open
 
-- **Border weight as identity — boxed fields vs Carbon's quieter defaults**
-  (**priority: pick this up first, next session** — user-flagged 2026-06-12).
-  Carbon's own defaults use far fewer boxes than we do: fields are filled with a
-  bottom border only (`reference/carbon` → text-input `_text-input.scss`,
-  `border-block-end` only), secondary buttons are a gray _fill_, tertiary is the
-  only outlined button (`_button.scss` → `button-theme(transparent,
-$button-tertiary, …)`), and tiles separate by layer steps with full borders
-  only behind an accessibility feature flag. Our fully-boxed fields/secondaries
-  are a recorded divergence (arch 09 §2 + §4) and the box-discipline rules now
-  contain the noise — the open question is whether to go further toward Carbon
-  (bottom-border-only fields, filled secondary) or keep the boxed look as
-  deliberate identity. An identity decision, not cleanup: it would repaint every
-  field in the app. Council seats: Carbon (canon above), NN/g (affordance of
-  boxed vs underlined inputs), a11y (3:1 non-text contrast for field boundaries
-  either way).
-
 - **Two visible "Export" buttons** (`App.tsx` header — workspace export;
   `ChartExport.tsx` in the preview header — per-chart export). Same label,
   different scope, both visible at once. Candidate fix: rename one ("Export