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/components/shared/SearchProviderIcon.tsx

@@ -0,0 +1,23 @@
+import { ProviderIcon } from '@lobehub/icons';
+import Tavily from '@lobehub/icons/es/Tavily';
+import { Search as SearchIcon } from 'lucide-react';
+
+/** Renders the correct icon for a given SearchProviderType */
+export function SearchProviderTypeIcon({ type, size = 20 }: { type: string; size?: number }) {
+  switch (type) {
+    case 'tavily':
+      return <Tavily.Color size={size} />;
+    case 'zhipu':
+      return <ProviderIcon provider="zhipu" size={size} type="color" />;
+    case 'bocha':
+      return <img src="/icons/bocha.ico" alt="Bocha" style={{ width: size, height: size }} />;
+    default:
+      return <SearchIcon size={size - 2} />;
+  }
+}
+
+export const PROVIDER_TYPE_LABELS: Record<string, string> = {
+  tavily: 'Tavily',
+  zhipu: '智谱',
+  bocha: '博查',
+};