Render chat and previews through the shared HTML cleaner

Why: The conversation and office fallbacks wrote marked output straight into the page, including converted docx HTML.
Evidence: html-sinks ratchet forbids new innerHTML writes outside @ui safeHtml.
Impact: Conversation keeps line-break rendering. Unsafe links are stripped after docx and pptx preview. dompurify is deduped with the UI package.
Refs: feature/sillytavern-review
Co-authored-by: Cursor <cursoragent@cursor.com>

src/components/Conversation.tsx

@@ -1,9 +1,8 @@
 // 中栏：消息流（Part 渲染器注册表）+ 流式渲染 + 过程折叠 + HITL 卡片 + 输入区（4.4）。
 // 重设计方案 阶段④：折叠区全部迁 @ui Collapsible（<details> 已禁）；工具调用块走
 // ToolBlock 契约（运行态扫光、完成边沿收起、展开态记忆）；live 行扫光 + 已工作计时。
-import { Icon, Avatar, BrandMark, Collapsible, getPersistedOpen, setPersistedOpen } from '@ui'
+import { Icon, Avatar, BrandMark, Collapsible, getPersistedOpen, setPersistedOpen, SafeMarkdown } from '@ui'
 import { useEffect, useMemo, useRef, useState } from 'react'
-import { marked } from 'marked'
 import { api } from '../api'
 import { store, useStore, activeRun, type LiveState, type ContextObs } from '../store'
 import { scrollRatio, scrollTopForRatio } from '../scrollsync'
@@ -19,15 +18,15 @@ function hasFiles(dt: DataTransfer | null): boolean {
   return !!dt && Array.from(dt.types).includes('Files')
 }
 
-// marked 走标准 Markdown 语义（不开 breaks）：模型输出按块级排版渲染，
-// 行内换行交给段落折叠，避免与 CSS 块间距叠加出松散排版。
+// 对话正文沿用 breaks：卡片渲染器曾经把全局 marked 设成 breaks，
+// 去重后的同一份 marked 让对话也按行内换行显示。这里显式保持这个效果。
 
 // Part 渲染器注册表：按类型查表；未知类型静默忽略（前向兼容）。
 function PartView({ part, live }: { part: Part; live?: boolean | null }) {
   switch (part.type) {
     case 'text':
-      return <div className={live ? 'part-text cursor-blink' : 'part-text'}
-        dangerouslySetInnerHTML={{ __html: marked.parse(markMissingArtifacts(part.text ?? '', id => !!findArtifact(id))) as string }} />
+      return <SafeMarkdown className={live ? 'part-text cursor-blink' : 'part-text'} breaks
+        markdown={markMissingArtifacts(part.text ?? '', id => !!findArtifact(id))} />
     case 'thinking':
       // 流式期间展开可实时看到思考；run 终态后收进过程折叠区，默认收起。
       //（此单件形态用于过程组之外散落的思考；组内思考由 ProcessParts 渲染。）