fix(a11y): reduced-motion for spinner/call-avatar; tap-to-skip boot; AA accent contrast

- SendingSpinClass and CallAvatarAnimation respect prefers-reduced-motion
  (static opacity fallback), matching MsgAppearClass.
- Terminal boot overlay dismisses on click/tap and is aria-hidden.
- Primary.Main: Midnight #6b7ca8 -> #6f80aa (4.29 -> 4.51:1), Lotus
  Terminal Light #c44e00 -> #ba4a00 (4.14 -> 4.52:1), hue preserved.

Fixes #84
Fixes #86
Fixes #52

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/colors.css.ts

@@ -500,7 +500,9 @@ export const midnightTheme = createTheme(color, {
   },
 
   Primary: {
-    Main: '#6b7ca8',
+    // #6b7ca8 measured 4.29:1 against Background.Container (#111827), below
+    // WCAG AA 4.5:1. Lightened along the same hue/saturation to 4.51:1.
+    Main: '#6f80aa',
     MainHover: '#7989b1',
     MainActive: '#8493b8',
     MainLine: '#8f9dbf',
@@ -651,7 +653,9 @@ export const lotusTerminalLightTheme = createTheme(color, {
     OnContainer: '#2d3d56',
   },
   Primary: {
-    Main: '#c44e00',
+    // #c44e00 measured 4.14:1 against Background.Container (#edf0f5), below
+    // WCAG AA 4.5:1. Darkened along the same hue/saturation to 4.52:1.
+    Main: '#ba4a00',
     MainHover: '#a33f00',
     MainActive: '#8f3700',
     MainLine: '#d45800',