Mark recap Case-B design retrofit done; log cleanup-execution learnings

- Flip recap's Case-B /design backfill from "in flight" -> done in
  ROADMAP/AGENTS: contract extracted + two-phase conformance cleanup
  shipped (recap app 0.2.161).
- Add three cleanup-execution Field notes to guides/design.md:
  CSS-value-position var-ify scoping, exclude standalone no-:root
  exports, border-radius-clamp capsule snapping.
- Note the standalone-export literal-hex exception in design-checker.md's
  Color dimension.

guides/design-checker.md

@@ -40,7 +40,10 @@ A path to the repo to audit (default: the current working directory).
 
 - **Color** — UI colors trace to a token in `tokens.tokens.json` (directly or via a CSS
   custom property generated from it). Hardcoded hex/rgb values that don't match any token are
-  violations; off-palette colors are violations.
+  violations; off-palette colors are violations. **Exception — standalone generated documents**
+  (a share/print/email export that ships its own `<style>` with no `:root`): they legitimately use
+  literal hex because `var()` can't resolve without the token block, so audit them against the token
+  *values* and don't flag the literal hex itself as a violation.
 - **Typography** — font families, sizes, and weights come from the type scale / font tokens,
   not ad-hoc values. Headings and body follow the `DESIGN.md` typography rules.
 - **Spacing & layout** — margins, padding, and gaps use the spacing scale; layout density and