adopt CYBER neon-dark theme tokens

Replace the Pure Ink light/dark/comic theme system with the CYBER
single-theme dark palette from the reviewed prototype: OKLCH surfaces,
one neon-cyan accent, and monospace-first typography.

Arco components were reading colors from arco.css because no
ConfigProvider was mounted, so the theme values in arco-theme.ts never
took effect. Bridge CYBER into Arco through its --color-* variables in
global.scss instead, and align arco-theme.ts to match.

Brightness and style switches are gone: useTheme now pins dark, the
comic font faces and locale keys are removed, and ThemeSwitch.vue is
deleted along with its sidebar slot and display setting.

packages/client/src/styles/arco-theme.ts

@@ -1,14 +1,20 @@
-// Arco Design theme tokens for hermes-ui (Phase 005 baseline).
-// Dark mode is carried by `body[arco-theme='dark']` CSS overrides, not a second theme object.
-// See docs/ui-baseline.md for the frozen visual language.
+// Arco Design theme tokens for hermes-ui — CYBER.
+//
+// 这些值是「参考值」，不是运行时来源：项目没有挂 ConfigProvider，Arco 的实际外观
+// 由 styles/global.scss 里的 --color-* 变量覆盖决定（见那里的 Arco token bridge）。
+// 保留本文件是为了让读取 token 的人能在一处看到意图，以及给测试一个可断言的锚点。
+// 改色时请同时改 global.scss 的 Arco token bridge，两处保持一致。
 export const arcoTheme = {
-  // 延续旧版克制灰阶
-  colorPrimary: '#2f2f2f',
-  colorBgLayout: '#fafafa',
-  colorBgContainer: '#ffffff',
+  // 霓虹青 oklch(0.805 0.148 188) ≈ rgb(45, 212, 191)
+  colorPrimary: '#2dd4bf',
+  // 页面底 / 卡片底，对应 oklch(0.155 0.012 250) 与 oklch(0.130 0.012 250)
+  colorBgLayout: '#1a1d23',
+  colorBgContainer: '#14171c',
   borderRadius: 6,
-  fontFamily: 'Inter, system-ui, -apple-system, sans-serif',
-  fontFamilyMono: '"JetBrains Mono", "Fira Code", monospace',
+  fontFamily:
+    '-apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Segoe UI", Roboto, sans-serif',
+  fontFamilyMono:
+    'ui-monospace, "JetBrains Mono", "SF Mono", Menlo, "Cascadia Code", monospace',
 }
 
 export type ArcoTheme = typeof arcoTheme