Reconcile DESIGN.md debt note: admin SPA can't @import (rust-embed)

The palette-consolidation task was dropped during the 2026-06-18 adjudication
because the rust-embedded admin SPA can't @import at runtime, so consolidation
there is a verbatim re-copy that removes no duplication. Update the §9 debt note
accordingly and drop the now-stale ROADMAP pointer.

design/DESIGN.md

@@ -137,6 +137,9 @@ When building or changing a Keysat UI:
   icons, sentence-case labels, no emoji.
 - If a needed value genuinely isn't in the tokens, **add it to the tokens file** (and ideally
   `palette.css`) rather than inlining a one-off — keep the contract the single source of truth.
-- Known debt (see ROADMAP): the three surfaces currently inline their own copy of the
-  variables. Prefer importing `design/brand/palette.css`; when you touch a surface, move it
-  toward that shared source rather than perpetuating a private copy.
+- Known debt: the three surfaces inline their own copy of the variables. For **landing and
+  docs** (static files) prefer importing `design/brand/palette.css` when you touch them. The
+  **admin SPA is rust-embedded and cannot `@import` at runtime**, so its copy stays inline by
+  necessity — keep it a verbatim copy of `palette.css`, don't let it drift. (A blanket
+  "consolidate all three onto `palette.css`" task was adjudicated and **dropped** 2026-06-18
+  for exactly this reason — it can't remove the admin duplication it targets.)