feat: 增强编辑器链接对话框并统一图片插入选择器

链接支持网址/文字与站内搜索，新标签由全站设置控制；文章与评论共用已上传图片选择器。

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

frontend/src/utils/markdownFormat.ts

@@ -122,9 +122,12 @@ export function insertMarkdownLink(
   value: string,
   url: string,
   onChange: ChangeHandler,
+  opts?: { text?: string },
 ) {
   const { selectionStart, selectionEnd } = textarea;
-  const selected = value.slice(selectionStart, selectionEnd) || '链接文字';
+  const selected = opts?.text?.trim()
+    || value.slice(selectionStart, selectionEnd)
+    || '链接文字';
   const insert = `[${selected}](${url})`;
   const next = value.slice(0, selectionStart) + insert + value.slice(selectionEnd);
   applyTextareaChange(