feat(compose): 正文内嵌隐藏块并升级 Markdown 编辑器

去掉整帖可见性表单，改为 :::hide 按块脱敏；工具栏补齐代码块、链接/图片对话框与粘贴拖拽上传。

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/app/post/[id]/edit/EditPostClient.tsx

@@ -9,8 +9,6 @@ type Props = {
   initialContent: string;
   initialTags: string;
   initialPostType?: string;
-  initialContentAccess?: string;
-  initialAccessPoints?: number;
   initialTypeMeta?: string;
   initialAttachments?: PostAttachment[];
   canEditPollOptions?: boolean;
@@ -26,8 +24,6 @@ export default function EditPostClient({
   initialContent,
   initialTags,
   initialPostType,
-  initialContentAccess,
-  initialAccessPoints,
   initialTypeMeta,
   initialAttachments,
   canEditPollOptions,
@@ -44,8 +40,6 @@ export default function EditPostClient({
       initialContent={initialContent}
       initialTags={initialTags}
       initialPostType={initialPostType}
-      initialContentAccess={initialContentAccess}
-      initialAccessPoints={initialAccessPoints}
       initialTypeMeta={initialTypeMeta}
       initialAttachments={initialAttachments}
       canEditPollOptions={canEditPollOptions}