feat(ios): switch accent to desktop amber-gold theme (was indigo)

Match the desktop/web theme (public/style.css): accent #E3A64A gold (dark) /
#C9892F (light) replacing the indigo, +onAccent #1A1305 dark ink for gold-fill
buttons, +accentSoft. Status colors realigned to the web warm palette
(#46D07F/#F5B14C/#FF6B6B). Terminal canvas fixed to the desktop warm-dark
(#100F0D bg / #ECE9E3 fg) with gold caret/selection. DSButtonStyle primary now
uses onAccent (dark) instead of white for contrast on gold. All via the single
accent token + DS palette — no scattered edits.

Verified: iPhone 16 290 + iPad Pro 11 290 tests green (DesignSystemTests assert
the exact gold + web-status RGB in both schemes).

ios/App/WebTerm/DesignSystem/Primitives.swift

@@ -150,7 +150,10 @@ struct DSButtonStyle: ButtonStyle {
 
         private var foreground: Color {
             switch kind {
-            case .primary, .destructive: return .white
+            // Gold accent fill needs DARK ink for contrast (mirrors web
+            // --on-accent), NOT white. Red destructive fill keeps white.
+            case .primary: return DS.Palette.onAccent
+            case .destructive: return .white
             case .secondary: return DS.Palette.accent
             }
         }