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>

pnpm-lock.yaml

@@ -158,6 +158,9 @@ importers:
       '@fontsource-variable/jetbrains-mono':
         specifier: ^5.2.8
         version: 5.2.8
+      '@fontsource/orbitron':
+        specifier: ^5.2.0
+        version: 5.2.8
       '@xterm/addon-fit':
         specifier: 0.10.0
         version: 0.10.0(@xterm/xterm@5.5.0)
@@ -839,6 +842,9 @@ packages:
   '@fontsource-variable/jetbrains-mono@5.2.8':
     resolution: {integrity: sha512-WBA9elru6Jdp5df2mES55wuOO0WIrn3kpXnI4+W2ek5u3ZgLS9XS4gmIlcQhiZOWEKl95meYdvK7xI+ETLCq/Q==}
 
+  '@fontsource/orbitron@5.2.8':
+    resolution: {integrity: sha512-ruzrDl5vnqNykk5DZWY0Ezj4aeFZSbCnwJTc/98ojNJHSsHhlhT2r7rwQrA5sptmF8JtB8TQTAvlfRvcV28RPw==}
+
   '@hono/node-server@1.19.14':
     resolution: {integrity: sha512-GwtvgtXxnWsucXvbQXkRgqksiH2Qed37H9xHZocE5sA3N8O8O8/8FA3uclQXxXVzc9XBZuEOMK7+r02FmSpHtw==}
     engines: {node: '>=18.14.1'}
@@ -4705,6 +4711,8 @@ snapshots:
 
   '@fontsource-variable/jetbrains-mono@5.2.8': {}
 
+  '@fontsource/orbitron@5.2.8': {}
+
   '@hono/node-server@1.19.14(hono@4.12.18)':
     dependencies:
       hono: 4.12.18