feat: futuristic theme ladder + stacked landing banner

Add three opt-in dark themes (BooCode+, BooCode Classic, BooCode
Override) plus an in-place Ember polish, on a class-scoped effects
engine: matrix rain, a neon grid field, and frosted glass, all gated
by a localStorage "Animated background" toggle and prefers-reduced-
motion. Extend the server theme_id whitelist so the new ids persist,
and replace the Home landing wordmark with the stacked mascot +
wordmark banner.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/web/src/main.tsx

@@ -3,6 +3,9 @@
 // imports so the @font-face CSS lands before any component-tree render.
 import '@fontsource-variable/inter';
 import '@fontsource-variable/jetbrains-mono';
+// Orbitron weight-800 only — used for the BooCode Classic display wordmark.
+// Static @fontsource (not variable) pinned to a single weight to keep bundle small.
+import '@fontsource/orbitron/800.css';
 import React from 'react';
 import ReactDOM from 'react-dom/client';
 import App from './App';