fix(a11y): WCAG AA contrast retune for the Otter Orange palette (#567)

Fixes #557. Vivid fill, ink label: brand #E07832 stays on fills while primary-foreground flips to #1A1814 (5.83:1); new theme-aware ink tokens carry orange, destructive, and success text roles; opacity-modified text purged; landing, demo, and the docs fund button retuned. Guarded by a CSS-parsing unit contrast test, rebuilt axe baselines with zero contrast entries, a new landing axe smoke, and fully regenerated darwin visual baselines.

apps/web/src/components/files/file-details.tsx

@@ -496,9 +496,7 @@ export function FileDetails({ mobile = false }: FileDetailsProps) {
       <div className="flex-1">
         <div className="rounded-lg border border-border overflow-hidden">
           <div className="bg-primary/10 border-b border-border px-3 py-2">
-            <h4 className="text-sm font-semibold text-primary-dark dark:text-primary-light">
-              {t.files.fileDetailsHeading}
-            </h4>
+            <h4 className="text-sm font-semibold text-primary-ink">{t.files.fileDetailsHeading}</h4>
           </div>
           <div className="divide-y divide-border">
             <DetailRow label={t.files.name} value={details.originalName} />