fix(ui): give unchosen segments the tab trigger's readable dark tone

The muted foreground on the muted track reads 3.6:1 in the dark theme,
below WCAG AA. Tabs already solved this with the tab-inactive token;
Segmented now uses the same treatment, so both controls look alike.

src/components/ui/segmented.tsx

@@ -142,7 +142,7 @@ export function Segmented<T extends string>({
               stretch && "flex-1",
               checked
                 ? "bg-background text-foreground shadow-sm"
-                : "text-muted-foreground hover:text-foreground",
+                : "text-foreground/75 hover:text-foreground dark:text-tab-inactive dark:hover:text-foreground",
             )}
           >
             {Icon ? (