feat: Luminous Depth UI redesign

Complete visual overhaul of the Aryx application with the Luminous Depth
design language — blue-tinted dark surfaces, brand gradient accents,
glass-morphism effects, and refined typography.

Design Foundation:
- New color system with CSS custom properties for all surfaces, borders,
  text, accents, and status colors
- Typography: Outfit (display), DM Sans (body), JetBrains Mono (code)
- Animations: accent-flow, thinking-wave, ambient-glow
- Utility classes: glass-surface, glow-border, brand-gradient-bg/text
- Light theme with cool-tinted whites and blue-tinted shadows

Components Updated:
- UI primitives (TextInput, SelectInput, ToggleSwitch, FormField, etc.)
- AppShell with ambient glow background
- Sidebar with brand gradient selection and accent-flow running bars
- ChatPane with semantic phase tinting and gradient user avatars
- WelcomePane with nebula background and motion entrance animations
- All chat banners (Approval, UserInput, PlanReview, MCP Auth, etc.)
- ActivityPanel and RunTimeline with glass-surface cards
- Settings panels, modals, and editor shells
- TerminalPanel with harmonized ANSI palette
- PatternGraph nodes with glass-surface styling
- MarkdownComposer toolbar

Zero hardcoded zinc/indigo color classes remain in renderer components.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/renderer/components/ui/ToggleSwitch.tsx

@@ -10,8 +10,8 @@ export function ToggleSwitch({ enabled, size = 'md' }: ToggleSwitchProps) {
 
   return (
     <span
-      className={`relative inline-flex ${trackSize} shrink-0 items-center rounded-full transition-colors ${
-        enabled ? 'bg-indigo-500' : 'bg-zinc-700'
+      className={`relative inline-flex ${trackSize} shrink-0 items-center rounded-full transition-all duration-200 ${
+        enabled ? 'brand-gradient-bg shadow-[0_0_8px_rgba(36,92,249,0.3)]' : 'bg-[var(--color-surface-3)]'
       }`}
     >
       <span