docs(design): Fjord stays a fifth scheme beside Midnight

The trial is over: the owner kept it. The trial wording goes from the
tokens, the scheme list, the lab and DESIGN; B2's own-hue rule still
binds any new scheme.

frontend/src/lib/theme.ts

@@ -11,8 +11,8 @@ export const SCHEMES: { id: Scheme; name: string; swatch: string }[] = [
   { id: "forest", name: "Forest", swatch: "#22d3ee" },
   { id: "slate", name: "Slate", swatch: "#e879f9" },
   { id: "matrix", name: "Matrix", swatch: "#86a05a" },
-  // A TRIAL outside B2 (Midnight's hue family, DESIGN.md decision log 2026-09-25): folded into
-  // Midnight or removed once the owner has tried it; a stored "fjord" then lands on the default.
+  // The one scheme outside B2's "own hue family": Midnight's navy with a calm steel accent, kept
+  // beside Midnight on purpose (DESIGN.md decision log, trial 2026-09-25, kept 2026-09-27).
   { id: "fjord", name: "Fjord", swatch: "#5aa1cb" },
 ];