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/scripts/clean-dts.cjs

@@ -0,0 +1,35 @@
+const fs = require('node:fs')
+const path = require('node:path')
+const process = require('node:process')
+
+const distDir = path.resolve(__dirname, '..', 'dist')
+const typesDir = path.join(distDir, 'types')
+
+function rewriteTypesEntry(content) {
+  return content
+    .replace(/from\s+(['"])\.\//g, 'from $1./types/')
+    .replace(/import\((['"])\.\//g, 'import($1./types/')
+}
+
+function referencesTypesDir(content) {
+  return /from\s+['"]\.\/types\/|import\(['"]\.\/types\//.test(content)
+}
+
+const sourcePath = path.join(typesDir, 'exports.d.ts')
+const targetPath = path.join(distDir, 'index.d.ts')
+
+if (fs.existsSync(targetPath)) {
+  const bundledContent = fs.readFileSync(targetPath, 'utf8')
+  if (!referencesTypesDir(bundledContent)) {
+    if (fs.existsSync(typesDir))
+      fs.rmSync(typesDir, { recursive: true, force: true })
+    console.log('Keeping bundled', targetPath)
+    process.exit(0)
+  }
+}
+
+if (fs.existsSync(sourcePath)) {
+  const content = rewriteTypesEntry(fs.readFileSync(sourcePath, 'utf8'))
+  fs.writeFileSync(targetPath, content)
+  console.log('Rewrote', targetPath, 'from', sourcePath)
+}