feat: add cover image functionality for articles

- Implemented `resolveApiURL` function to handle various URL formats.
- Updated `ArticleDetail` and `UpdateArticleRequest` interfaces to include `cover_asset_url`.
- Enhanced `ArticleEditorView` to manage cover image uploads, including a new `CoverPickerModal` component.
- Added cover image requirements logic in `cover-requirements.ts` to enforce platform-specific cover image rules.
- Modified backend services to handle cover image uploads and validations, including checks for required cover images for specific platforms.
- Improved error handling for cover image requirements during article publishing.

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

@@ -434,8 +434,15 @@ const zhCN = {
       platformsTitle: "发布平台",
       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: "发布前可先上传封面素材，当前只做本地预览。",
+      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。",
       coverUpload: "上传封面图",
+      coverReplace: "重新选择",
+      coverRemove: "移除封面",
+      coverSaved: "已保存封面素材",
+      coverOff: "封面图当前已关闭，开启后可上传并裁剪封面素材。",
+      coverTagRequired: "必传",
+      coverTagOptional: "可选",
       imagePrompt: "请输入图片地址",
       tablePicker: {
         empty: "拖拽选择表格尺寸",
@@ -573,7 +580,8 @@ const zhCN = {
       platformsTitle: "发布平台",
       platformsHint: "会优先回填文章里已选择且已绑定的账号，未绑定或本地登录态异常的平台不可选。",
       coverTitle: "封面图",
-      coverHint: "当前版本先使用封面素材 URL，后续可以接入上传与裁剪。",
+      coverHint: "默认关闭。点击上传后可选择或裁剪封面。",
+      coverUpload: "上传封面图",
       coverPlaceholder: "请输入封面素材 URL（可选）",
       messages: {
         success: "已提交 {count} 个平台发布任务",
@@ -581,6 +589,7 @@ 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",
         failureTitle: "发布失败",
         failureItem: "文章发布到平台【{platform}】失败【{reason}】",
         unknownFailure: "未知错误",
@@ -599,6 +608,46 @@ const zhCN = {
       copySuccess: "链接已复制",
     },
   },
+  coverPicker: {
+    title: "选择封面图",
+    tabs: {
+      local: "正文/本地上传",
+      ai: "AI封图",
+    },
+    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。",
+    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。",
+    recommendedRatio: "推荐比例",
+    recommendedSize: "推荐尺寸",
+    required: "必传",
+    optional: "可选",
+    zoom: "缩放",
+    fileLabel: "当前封面",
+    emptyTitle: "暂未选择发布平台",
+    emptyPlatforms: "选择发布平台后，这里会自动显示每个平台的封面要求。",
+    emptyHint: "支持 PNG、JPG、GIF、WebP，最大 10MB",
+    aiTitle: "AI 封图即将开放",
+    aiHint: "当前先支持本地上传和裁剪，后续会把 AI 生成封面接进这里。",
+    actions: {
+      upload: "本地上传",
+      reset: "重置取景",
+      remove: "移除封面",
+    },
+    notes: {
+      required: "该平台当前发布链路要求必须携带封面图，未上传时不能提交发布。",
+      optional: "该平台当前接入已支持独立封面，会复用当前裁剪结果完成发布。",
+      unsupported: "该平台当前接入暂不消费独立封面，会沿用正文内容或平台默认样式。",
+    },
+    messages: {
+      invalidType: "仅支持 PNG、JPG、GIF、WebP 图片",
+      tooLarge: "图片不能超过 10MB",
+      missingImage: "请先选择一张封面图",
+      missingArticle: "文章信息还没准备好，请刷新后重试",
+      imageLoadFailed: "封面图加载失败，请重新选择图片",
+    },
+  },
   brands: {
     eyebrow: "Brand Library",
     title: "品牌词库",