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/src/components/AdmonitionNode/AdmonitionNode.vue

@@ -0,0 +1,283 @@
+<script setup lang="ts">
+import { computed, getCurrentInstance, ref } from 'vue-demi'
+import { isLegacyVue26Vm } from '../../utils/vue26'
+import NodeRenderer from '../NodeRenderer'
+import LegacyNodesRenderer from '../NodeRenderer/LegacyNodesRenderer.vue'
+
+// 定义警告块节点类型
+export type AdmonitionKind = 'note' | 'info' | 'tip' | 'warning' | 'danger' | 'caution' | 'error'
+
+interface AdmonitionNode {
+  type: 'admonition'
+  kind: AdmonitionKind
+  title?: string
+  children: { type: string, raw: string }[]
+  raw: string
+  // 可选：是否支持折叠
+  collapsible?: boolean
+  // 可选：初始是否展开，默认 true
+  open?: boolean
+}
+
+// 接收 props（并在 script 中使用）
+const props = defineProps<{ node: AdmonitionNode, indexKey: number | string, isDark?: boolean, typewriter?: boolean, customId?: string }>()
+// 定义事件
+const emit = defineEmits(['copy'])
+
+// 不同类型的警告块图标（显式类型以便编辑器提示）
+const iconMap: Record<AdmonitionKind, string> = {
+  note: 'ℹ️',
+  info: 'ℹ️',
+  tip: '💡',
+  warning: '⚠️',
+  danger: '❗',
+  // 'error' is a common alias for 'danger' in some markdown flavors
+  error: '⛔',
+  caution: '⚠️',
+}
+
+// 当 title 为空时使用 kind 作为回退（首字母大写）
+const displayTitle = computed(() => {
+  if (props.node.title && props.node.title.trim().length)
+    return props.node.title
+  const k = props.node.kind || 'note'
+  return k.charAt(0).toUpperCase() + k.slice(1)
+})
+
+// 支持折叠：如果 props.node.collapsible 为 true，则依据 props.node.open 初始化
+const collapsed = ref<boolean>(props.node.collapsible ? !(props.node.open ?? true) : false)
+function toggleCollapse() {
+  if (!props.node.collapsible)
+    return
+  collapsed.value = !collapsed.value
+}
+
+// 为无障碍生成 ID（用于 aria-labelledby）
+const headerId = `admonition-${Math.random().toString(36).slice(2, 9)}`
+const instance = getCurrentInstance()
+const nestedRenderer = computed(() => {
+  const vm = instance?.proxy as any
+  return isLegacyVue26Vm(vm) ? LegacyNodesRenderer : NodeRenderer
+})
+</script>
+
+<template>
+  <div class="admonition" :class="[`admonition-${props.node.kind}`, props.isDark ? 'is-dark' : '']">
+    <div :id="headerId" class="admonition-header">
+      <span v-if="iconMap[props.node.kind]" class="admonition-icon">{{ iconMap[props.node.kind] }}</span>
+      <span class="admonition-title">{{ displayTitle }}</span>
+
+      <!-- 可选的折叠控制（放在 header 末端） -->
+      <button
+        v-if="props.node.collapsible"
+        class="admonition-toggle"
+        :aria-expanded="!collapsed"
+        :aria-controls="`${headerId}-content`"
+        :title="collapsed ? 'Expand' : 'Collapse'"
+        @click="toggleCollapse"
+      >
+        <span v-if="collapsed">▶</span>
+        <span v-else>▼</span>
+      </button>
+    </div>
+
+    <div
+      v-show="!collapsed"
+      :id="`${headerId}-content`"
+      class="admonition-content"
+      :aria-labelledby="headerId"
+    >
+      <component
+        :is="nestedRenderer"
+        :index-key="`admonition-${indexKey}`"
+        :nodes="props.node.children"
+        :custom-id="props.customId"
+        :typewriter="props.typewriter"
+        @copy="emit('copy', $event)"
+      />
+    </div>
+  </div>
+</template>
+
+<style scoped>
+/* 变量默认（浅色主题）*/
+.admonition {
+  --admonition-bg: #f8f8f8;
+  --admonition-border: #eaecef;
+  --admonition-header-bg: rgba(0, 0, 0, 0.03);
+  --admonition-text: #111827;
+  --admonition-muted: #374151;
+
+  --admonition-note-color: #448aff;
+  --admonition-tip-color: #00bfa5;
+  --admonition-warning-color: #ff9100;
+  --admonition-danger-color: #ff5252;
+
+  margin: 1rem 0;
+  padding: 0;
+  border-radius: 4px;
+  border-left: 4px solid var(--admonition-border);
+  background-color: var(--admonition-bg);
+  color: var(--admonition-text);
+  overflow: hidden;
+}
+
+.admonition-header {
+  padding: 0.5rem 1rem;
+  font-weight: 600;
+  display: flex;
+  align-items: center;
+  background-color: var(--admonition-header-bg);
+  color: var(--admonition-muted);
+}
+
+.admonition-icon {
+  margin-right: 0.5rem;
+  color: inherit;
+}
+
+.admonition-content {
+  padding: 0.5rem 1rem 1rem;
+  color: var(--admonition-text);
+}
+
+/* 各种类型只控制边框与 header 颜色（使用更轻的 header 背景，以免过于抢眼） */
+.admonition-note {
+  border-left-color: var(--admonition-note-color);
+}
+.admonition-note .admonition-header {
+  background-color: rgba(68, 138, 255, 0.06);
+  color: var(--admonition-note-color);
+}
+
+.admonition-info {
+  border-left-color: var(--admonition-note-color);
+}
+.admonition-info .admonition-header {
+  background-color: rgba(68, 138, 255, 0.06);
+  color: var(--admonition-note-color);
+}
+
+.admonition-tip {
+  border-left-color: var(--admonition-tip-color);
+}
+.admonition-tip .admonition-header {
+  background-color: rgba(0, 191, 165, 0.06);
+  color: var(--admonition-tip-color);
+}
+
+.admonition-warning {
+  border-left-color: var(--admonition-warning-color);
+}
+.admonition-warning .admonition-header {
+  background-color: rgba(255, 145, 0, 0.06);
+  color: var(--admonition-warning-color);
+}
+
+.admonition-danger {
+  border-left-color: var(--admonition-danger-color);
+}
+.admonition-danger .admonition-header {
+  background-color: rgba(255, 82, 82, 0.06);
+  color: var(--admonition-danger-color);
+}
+
+.admonition-error {
+  border-left-color: var(--admonition-danger-color);
+}
+.admonition-error .admonition-header {
+  background-color: rgba(255, 82, 82, 0.06);
+  color: var(--admonition-danger-color);
+}
+
+.admonition-caution {
+  border-left-color: var(--admonition-warning-color);
+}
+.admonition-caution .admonition-header {
+  background-color: rgba(255, 145, 0, 0.06);
+  color: var(--admonition-warning-color);
+}
+
+/* 修复：当一次性渲染大量内容并滚动到 AdmonitionNode 时，
+   内部 NodeRenderer（.markdown-renderer）使用 content-visibility: auto
+   可能导致占位高度很高但未及时绘制。这里在告示块内部禁用该优化，
+   保证内容按时渲染，避免“空白但很高”的现象。*/
+.admonition-content ::v-deep .markdown-renderer {
+  content-visibility: visible;
+  contain: content;
+  contain-intrinsic-size: 0px 0px;
+}
+
+/* 折叠按钮样式 */
+.admonition-toggle {
+  margin-left: auto;
+  background: transparent;
+  border: none;
+  color: inherit;
+  cursor: pointer;
+  padding: 0.25rem 0.5rem;
+  border-radius: 4px;
+  font-size: 0.9rem;
+}
+.admonition-toggle:focus {
+  outline: 2px solid rgba(0,0,0,0.08);
+  outline-offset: 2px;
+}
+
+/* 深色模式支持：支持 props.isDark（组件级）与系统偏好（媒体查询） */
+.admonition.is-dark {
+  --admonition-bg: #0b1220;
+  --admonition-border: rgba(255, 255, 255, 0.06);
+  --admonition-header-bg: rgba(255, 255, 255, 0.03);
+  --admonition-text: #e6eef8;
+  --admonition-muted: #cbd5e1;
+}
+
+/* 当组件通过 props.isDark 指定为暗色时，增强语义色块 */
+.admonition.is-dark .admonition-note .admonition-header,
+.admonition.is-dark .admonition-info .admonition-header {
+  background-color: rgba(68, 138, 255, 0.12);
+  color: var(--admonition-note-color);
+}
+.admonition.is-dark .admonition-tip .admonition-header {
+  background-color: rgba(0, 191, 165, 0.12);
+  color: var(--admonition-tip-color);
+}
+.admonition.is-dark .admonition-warning .admonition-header {
+  background-color: rgba(255, 145, 0, 0.12);
+  color: var(--admonition-warning-color);
+}
+.admonition.is-dark .admonition-danger .admonition-header {
+  background-color: rgba(255, 82, 82, 0.12);
+  color: var(--admonition-danger-color);
+}
+
+@media (prefers-color-scheme: dark) {
+  .admonition {
+    --admonition-bg: #0b1220;
+    --admonition-border: rgba(255, 255, 255, 0.06);
+    --admonition-header-bg: rgba(255, 255, 255, 0.03);
+    --admonition-text: #e6eef8;
+    --admonition-muted: #cbd5e1;
+  }
+
+  /* 在暗色里稍微增强 header 的语义色块 */
+  .admonition-note .admonition-header,
+  .admonition-info .admonition-header {
+    background-color: rgba(68, 138, 255, 0.12);
+    color: var(--admonition-note-color);
+  }
+  .admonition-tip .admonition-header {
+    background-color: rgba(0, 191, 165, 0.12);
+    color: var(--admonition-tip-color);
+  }
+  .admonition-warning .admonition-header {
+    background-color: rgba(255, 145, 0, 0.12);
+    color: var(--admonition-warning-color);
+  }
+  .admonition-danger .admonition-header {
+    background-color: rgba(255, 82, 82, 0.12);
+    color: var(--admonition-danger-color);
+  }
+}
+</style>

desktop/libs/markstream-vue/packages/markstream-vue2/src/components/AdmonitionNode/index.ts

@@ -0,0 +1,3 @@
+import AdmonitionNode from './AdmonitionNode.vue'
+
+export default AdmonitionNode