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/docs/guide/examples.md

@@ -0,0 +1,48 @@
+# Examples
+
+Short examples; see `playground` for interactive demos.
+
+## Streaming Markdown
+```vue
+<script setup lang="ts">
+import MarkdownRender from 'markstream-vue'
+import { ref } from 'vue'
+
+const content = ref('')
+const fullContent = `# Streaming Content\n\nThis text appears progressively...`
+let i = 0
+const interval = setInterval(() => {
+  if (i < fullContent.length) {
+    content.value += fullContent[i]
+    i++
+  }
+  else {
+    clearInterval(interval)
+  }
+}, 50)
+</script>
+
+<template>
+  <MarkdownRender :content="content" />
+</template>
+```
+
+## Typewriter + TypeScript example
+- Use `typewriter` prop to enable enter transition
+
+## Rendering with `nodes`
+- Call `parseMarkdownToStructure` from `stream-markdown-parser` and pass `nodes` to `MarkdownRender` for custom rendering.
+
+Try this — quickly stream a Markdown string with `typewriter` enabled:
+
+```vue
+<script setup lang="ts">
+import MarkdownRender from 'markstream-vue'
+
+const md = '# Streaming test\n\nThis text appears with a subtle enter animation.'
+</script>
+
+<template>
+  <MarkdownRender :content="md" :typewriter="true" />
+</template>
+```