新增: 导出 JSON + 导入 JSON + 打印/PDF 导出(P4)

- 工具栏新增三个按钮: 导出 JSON / 导入 JSON / 打印 PDF
- 导出 JSON: Blob 下载 store.exportJSON()
- 导入 JSON: 文件选择 + FileReader → store.importJSON()
- 打印 PDF: window.print() + @media print CSS,逐页 page-break
- 打印时隐藏编辑器/HUD/工具栏,只保留幻灯片内容
- 零新依赖(PDF 走浏览器原生打印)

src/App.vue

@@ -71,6 +71,49 @@ function onSave() {
 }
 function openAi() { switchTab('ai') }
 
+/* ---------- 导出/导入 ---------- */
+function onExportJson() {
+  const json = store.exportJSON()
+  const blob = new Blob([json], { type: 'application/json' })
+  const url = URL.createObjectURL(blob)
+  const a = document.createElement('a')
+  a.href = url
+  a.download = 'u-ppt-export.json'
+  a.click()
+  URL.revokeObjectURL(url)
+  toast('已导出 JSON')
+}
+
+function onImportJson() {
+  const input = document.createElement('input')
+  input.type = 'file'
+  input.accept = '.json,application/json'
+  input.onchange = () => {
+    const file = input.files?.[0]
+    if (!file) return
+    const reader = new FileReader()
+    reader.onload = () => {
+      try {
+        store.importJSON(reader.result as string)
+        toast('已导入')
+      } catch (e: any) {
+        toast('导入失败：' + (e?.message || String(e)))
+      }
+    }
+    reader.readAsText(file)
+  }
+  input.click()
+}
+
+function onExportPdf() {
+  // 用浏览器打印 + @media print CSS 实现 PDF 导出
+  // 演示模式的 slide-layer 已有 print 样式
+  document.body.classList.add('printing')
+  window.print()
+  setTimeout(() => document.body.classList.remove('printing'), 500)
+  toast('在打印对话框中选择「另存为 PDF」')
+}
+
 /* ---------- 全局快捷键（编辑模式） ---------- */
 function onKey(e: KeyboardEvent) {
   if (document.body.dataset.mode === 'present') return
@@ -119,6 +162,9 @@ onUnmounted(() => {
       @open-ai="openAi"
       @save="onSave"
       @open-templates="templateVisible = true"
+      @export-json="onExportJson"
+      @import-json="onImportJson"
+      @export-pdf="onExportPdf"
     />
 
     <div class="editor-body">

src/components/editor/Toolbar.vue

@@ -13,6 +13,9 @@ const emit = defineEmits<{
   (e: 'open-ai'): void
   (e: 'save'): void
   (e: 'open-templates'): void
+  (e: 'export-json'): void
+  (e: 'import-json'): void
+  (e: 'export-pdf'): void
 }>()
 
 const themeKeys = Object.keys(themes)
@@ -70,6 +73,9 @@ defineProps<{ disabledActions?: string[] }>()
       <span class="sep"></span>
       <button class="btn" data-action="library" title="我的演示文库" @click="action('library')">📁 文库</button>
       <button class="btn" data-action="save" title="保存到文库" :disabled="disabledActions?.includes('save')" @click="action('save')">💾 保存</button>
+      <button class="btn" data-action="export-json" title="导出 JSON" @click="emit('export-json')">📤 导出</button>
+      <button class="btn" data-action="import-json" title="导入 JSON" @click="emit('import-json')">📥 导入</button>
+      <button class="btn" data-action="export-pdf" title="打印/导出 PDF" @click="emit('export-pdf')">🖨 PDF</button>
       <button class="btn" data-action="open-ai" title="打开 AI 助手" @click="action('open-ai')">🤖 AI</button>
       <button class="btn" data-action="reset" title="重置为内置示例" :disabled="disabledActions?.includes('reset')" @click="action('reset')">⟲ 重置</button>
       <button class="btn primary" data-action="present" title="开始演示 (F5)" :disabled="disabledActions?.includes('present')" @click="action('present')">▶ 演示</button>

src/styles/present.css

@@ -121,3 +121,18 @@
   .present-stage .slide-inner.animated .el[data-type="list"] .li { opacity: 1 !important; animation: none !important; }
   .slide-inner.enter-next, .slide-inner.enter-prev { animation: none !important; }
 }
+
+/* ===== 打印 / 导出 PDF ===== */
+@media print {
+  /* 隐藏编辑器、工具栏、HUD、toast */
+  .app-editor, .toolbar, .canvas-status, .present-hud, .toast, .panel-tabs, .side-panel, .thumb-bar { display: none !important; }
+  body.printing .app-present { display: block !important; }
+  body.printing .present-stage { position: static; }
+  body.printing .present-hud { display: none !important; }
+  body.printing .slide-layer { transform: none !important; }
+  body.printing .slide-inner { page-break-after: always; }
+  /* 编辑模式打印：隐藏画布手柄等编辑装饰 */
+  .handle, .canvas-placeholder { display: none !important; }
+  /* 如果不在演示模式，打印当前页 */
+  body.printing:not(:has(.app-present:not(.hidden))) .canvas-stage { display: block; }
+}