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/test/height.test.ts

@@ -0,0 +1,31 @@
+import { describe, expect, it } from 'vitest'
+import { createHeightManager } from '../src/utils/height'
+
+// polyfill requestAnimationFrame for test environment
+if (typeof (globalThis as any).requestAnimationFrame === 'undefined') {
+  ;(globalThis as any).requestAnimationFrame = (cb: FrameRequestCallback) => setTimeout(() => cb(Date.now()), 0)
+  ;(globalThis as any).cancelAnimationFrame = (id: number) => clearTimeout(id)
+}
+
+describe('createHeightManager', () => {
+  it('applies computed height and suppresses during application', async () => {
+    // create a fake container
+    const container = { style: { height: '' } } as unknown as HTMLElement
+    let computeCalls = 0
+    const cm = () => {
+      computeCalls++
+      return 100 + computeCalls
+    }
+    const m = createHeightManager(container, cm)
+    // first update should set height
+    m.update()
+    // wait a tick for RAF via requestAnimationFrame
+    await new Promise(res => setTimeout(res, 0))
+    expect(container.style.height).toMatch(/px$/)
+    // second update with same computed value should not change
+    m.update()
+    await new Promise(res => setTimeout(res, 0))
+    expect(container.style.height).not.toBe('')
+    m.dispose()
+  })
+})