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/libs/markstream-vue/tsconfig.json

@@ -0,0 +1,29 @@
+{
+  "compilerOptions": {
+    "target": "ESNext",
+    "jsx": "preserve",
+    "lib": ["DOM", "ESNext"],
+    "baseUrl": ".",
+    "module": "ESNext",
+    "moduleResolution": "Node",
+    "paths": {
+      "@/*": ["src/*"],
+      "markstream-vue": ["src/exports.ts"],
+      // Ensure TypeScript can resolve the local workspace package without a build step in CI
+      "stream-markdown-parser": ["packages/markdown-parser/src/index.ts"],
+      "stream-markdown-parser/*": ["packages/markdown-parser/src/*"]
+    },
+    "resolveJsonModule": true,
+    "types": ["vite/client", "vue"],
+    "allowJs": true,
+    "declaration": true,
+    "declarationMap": true,
+    "emitDeclarationOnly": false,
+    "allowSyntheticDefaultImports": true,
+    "esModuleInterop": true,
+    "isolatedModules": true,
+    "skipLibCheck": true
+  },
+  "include": ["src/**/*", "./src/shims-vue.d.ts"],
+  "exclude": ["node_modules", "dist", "playground"]
+}