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/package.json

@@ -13,6 +13,7 @@
     "@boocode/contracts": "workspace:*",
     "@fontsource-variable/inter": "^5.2.8",
     "@fontsource-variable/jetbrains-mono": "^5.2.8",
+    "@fontsource/orbitron": "^5.2.0",
     "@xterm/addon-fit": "0.10.0",
     "@xterm/addon-search": "^0.15.0",
     "@xterm/addon-web-links": "0.11.0",