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/packages/markstream-vue2/tsconfig.json

@@ -0,0 +1,18 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "baseUrl": ".",
+    "rootDir": "./src",
+    "paths": {
+      "@/*": ["src/*"],
+      "stream-markdown-parser": ["../markdown-parser/dist/index.d.ts"],
+      "stream-markdown-parser/*": ["../markdown-parser/dist/*"]
+    },
+    "types": [],
+    "declaration": true,
+    "declarationMap": false,
+    "emitDeclarationOnly": true,
+    "outDir": "./dist"
+  },
+  "include": ["src/**/*", "src/**/*.vue"]
+}