feat(publish/dongchedi): publish via page context with cover and conservative HTML

懂车帝发布闸现走 Playwright/WebContents 内的 fetch，附带 CSRF token、自动
draft+commit 两步保存，并在前置流程中把正文 HTML 收敛到 p/strong/img、表格
降级为段落、过滤本地素材 URL。同步把懂车帝纳入封面强制平台，更新中英文
提示与错误码文案。

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/admin-web/src/i18n/messages/en-US.ts

@@ -900,7 +900,7 @@ const enUS = {
       platformsHint: "This stays in sync with Media Management so you can edit the article's publish platforms directly.",
       coverTitle: "Cover image",
       coverHint: "Off by default. Once uploaded, the cover is saved with the article.",
-      coverRequired: "Baijiahao is selected, so the cover image becomes required.",
+      coverRequired: "A selected publishing platform requires a cover image.",
       coverUpload: "Upload cover image",
       coverReplace: "Choose again",
       coverRemove: "Remove cover",
@@ -1060,7 +1060,7 @@ const enUS = {
         partial: "Publish finished with {success} succeeded and {failed} failed.",
         partialTitle: "Partial publish failure",
         selectPlatform: "Choose at least one available platform first.",
-        coverRequired: "Baidu Baijiahao is selected. Please upload a cover image first.",
+        coverRequired: "A selected publishing platform requires a cover image. Please upload one first.",
         failureTitle: "Publish failed",
         failureItem: "Publishing to [{platform}] failed: [{reason}]",
         unknownFailure: "Unknown error",
@@ -1088,10 +1088,10 @@ const enUS = {
     dropzoneTitle: "Upload image",
     dropzoneHint: "Supports PNG, JPG, GIF, and WebP up to 10MB. Uploads are converted to WebP in the browser first.",
     previewTitle: "Cover crop preview",
-    previewHintLocked: "Baijiahao is selected, so the cover will be exported as 16:9 when you confirm.",
+    previewHintLocked: "A selected platform requires a fixed cover ratio, so the cover will be exported using the current platform requirement.",
     previewHintFree: "There is no forced cover ratio right now. You can upload the original image directly or adjust framing before confirming.",
     requirementsTitle: "Platform requirements",
-    requirementsHint: "Requirements switch automatically based on the selected publish platforms. Baijiahao is mandatory.",
+    requirementsHint: "Requirements switch automatically based on the selected publish platforms. Baijiahao and Dongchedi require a cover image.",
     recommendedRatio: "Recommended ratio",
     recommendedSize: "Recommended size",
     required: "Required",

apps/admin-web/src/i18n/messages/zh-CN.ts

@@ -907,7 +907,7 @@ const zhCN = {
       platformsHint: "这里会同步媒体管理中的平台和绑定状态，支持直接编辑文章的发布平台。",
       coverTitle: "封面图",
       coverHint: "默认关闭。上传后会保存为文章封面素材。",
-      coverRequired: "已选择百家号，封面图为必传项。",
+      coverRequired: "已选择需要封面的发布平台，封面图为必传项。",
       coverUpload: "上传封面图",
       coverReplace: "重新选择",
       coverRemove: "移除封面",
@@ -1067,7 +1067,7 @@ const zhCN = {
         partial: "发布执行完成，成功 {success} 个，失败 {failed} 个",
         partialTitle: "部分发布失败",
         selectPlatform: "请先选择至少一个可发布的平台",
-        coverRequired: "已选择百家号，请先上传封面图",
+        coverRequired: "已选择需要封面的发布平台，请先上传封面图",
         failureTitle: "发布失败",
         failureItem: "文章发布到平台【{platform}】失败【{reason}】",
         unknownFailure: "未知错误",
@@ -1095,10 +1095,10 @@ const zhCN = {
     dropzoneTitle: "上传图片",
     dropzoneHint: "支持 PNG、JPG、GIF、WebP，上传前会在前端转为 WebP，最大 10MB",
     previewTitle: "封面裁剪预览",
-    previewHintLocked: "已选择百家号，确认时会按 16:9 输出封面。",
+    previewHintLocked: "已选择需要固定封面比例的平台，确认时会按当前平台要求输出封面。",
     previewHintFree: "当前不限制封面比例，可直接上传原图；如需调整也可拖拽缩放后再确认。",
     requirementsTitle: "平台封面要求",
-    requirementsHint: "会根据当前选中的发布平台自动切换要求，百家号为强制上传。",
+    requirementsHint: "会根据当前选中的发布平台自动切换要求，百家号和懂车帝为强制上传。",
     recommendedRatio: "推荐比例",
     recommendedSize: "推荐尺寸",
     required: "必传",

apps/admin-web/src/lib/cover-requirements.ts

@@ -33,6 +33,15 @@ const requirementCatalog: Record<string, Partial<PlatformCoverRequirement>> = {
     outputHeight: 800,
     priority: 100,
   },
+  dongchedi: {
+    required: true,
+    supportMode: "native",
+    aspectRatio: 4 / 3,
+    aspectLabel: "4:3",
+    outputWidth: 1200,
+    outputHeight: 900,
+    priority: 90,
+  },
 };
 
 export function getPlatformCoverRequirements(platformIds?: Array<string | null | undefined>): PlatformCoverRequirement[] {

apps/admin-web/src/lib/errors.ts

@@ -50,7 +50,7 @@ const errorMessageMap: Record<string, string> = {
   question_limit_reached: "当前关键词下的问题数量已达上限",
   brand_not_found: "品牌不存在或已删除",
   keyword_not_found: "关键词不存在或已删除",
-  publish_cover_required: "已选择百家号，请先上传封面图",
+  publish_cover_required: "当前选择的平台要求上传封面图，请先上传封面图",
   desktop_account_client_missing: "所选账号还没有绑定桌面客户端，暂时无法发布",
   desktop_account_not_found: "所选桌面账号不存在，请刷新后重试",
   desktop_client_offline: "当前登录账号的桌面客户端未在线，请先打开 desktop-client",