feat(desktop): embed BoosAPI Desktop client as a subproject

Vendor the rebranded BoosAPI Desktop client (Tauri + Vue) into metapi as
a monorepo subdirectory under desktop/. Source only — node_modules,
dist, Cargo target and the upstream .git history are excluded.

desktop/ keeps its own independent Cargo workspace (desktop/src-tauri
with crates/*); it is not part of the backend boosapi crate, so a
`cargo check` at the metapi root still compiles only the backend. Build
the desktop app from desktop/src-tauri per desktop/README.md.

Note: app icons are still placeholder assets pending the final BoosAPI
logo. The updater signing keys live outside the repo and are not
included.

desktop/src/constants/codeThemes.ts

@@ -0,0 +1,24 @@
+export const SHIKI_LIGHT_THEMES = [
+  'catppuccin-latte', 'everforest-light', 'github-light', 'github-light-default',
+  'github-light-high-contrast', 'light-plus', 'material-theme-lighter', 'min-light',
+  'one-light', 'rose-pine-dawn', 'slack-ochin', 'snazzy-light', 'solarized-light',
+  'vitesse-light',
+] as const;
+
+export const SHIKI_DARK_THEMES = [
+  'andromeeda', 'aurora-x', 'ayu-dark', 'catppuccin-frappe', 'catppuccin-macchiato',
+  'catppuccin-mocha', 'dark-plus', 'dracula', 'dracula-soft', 'everforest-dark',
+  'github-dark', 'github-dark-default', 'github-dark-dimmed', 'github-dark-high-contrast',
+  'houston', 'kanagawa-dragon', 'kanagawa-wave', 'laserwave', 'material-theme',
+  'material-theme-darker', 'material-theme-ocean', 'material-theme-palenight', 'min-dark',
+  'monokai', 'night-owl', 'nord', 'one-dark-pro', 'poimandres', 'red', 'rose-pine',
+  'rose-pine-moon', 'slack-dark', 'solarized-dark', 'synthwave-84', 'tokyo-night',
+  'vesper', 'vitesse-black', 'vitesse-dark',
+] as const;
+
+export function formatThemeName(id: string): string {
+  return id
+    .split('-')
+    .map((w) => w.charAt(0).toUpperCase() + w.slice(1))
+    .join(' ');
+}