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/stream-monaco/.prettierignore

@@ -0,0 +1,12 @@
+packages/*/CHANGELOG.md
+playground-temp/
+dist/
+temp/
+LICENSE.md
+pnpm-lock.yaml
+pnpm-workspace.yaml
+playground/tsconfig-json-load-error/has-error/tsconfig.json
+playground/html/invalid.html
+playground/html/valid.html
+playground/worker/classic-worker.js
+.history