feat(theme): complete redesign to Cyber-Cinematic Glass (Stitch)

Replace the legacy Apple TV-style purple/cyan theme with the full
Google Stitch Cyber-Cinematic Glass design system across the
entire app (desktop + mobile).

- New Material 3 dark ColorScheme: background #121317, primary
  #adc6ff, primaryContainer #4b8eff, surface containers, etc.
- Typography: Space Grotesk (headlines) + Inter (body/labels)
- 3-level glassmorphism via GlassContainer: base, glass, floating
- Primary gradient: #007AFF → #00C6FF with blue glow effects
- Removed old compatibility aliases (focusColor, border, textPrimary,
  textSecondary); all code now uses semantic Stitch tokens
- Systematically replaced all Colors.white/black/red/grey and
  GoogleFonts.roboto/outfit with Stitch equivalents
- All 36 lib/ files updated, zero compilation errors

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

pubspec.yaml

@@ -38,6 +38,7 @@ dependencies:
   google_fonts: ^6.2.1
   cached_network_image: ^3.3.1
   pointer_interceptor: ^0.10.1
+  material_symbols_icons: ^4.2801.1
   
   # Security
   crypto: ^3.0.3