fix(attachments): 文本附件打开中文乱码——aiohttp FileResponse按扩展名猜Content-Type不附charset,text/plain无charset浏览器按ISO-8859-1解UTF-8;服务端显式设charset=utf-8,未知扩展名纯文本归text/plain内联

wwwroot/api/ticket_attachment.dspy

@@ -30,4 +30,21 @@ else:
     headers['Content-Disposition'] = (
         'inline; filename="%s"; filename*=UTF-8\'\'%s' % (fname, safe_name))
 
+# 文本类显式带 charset=utf-8：aiohttp FileResponse 按扩展名猜 Content-Type 不附
+# charset，text/plain 无 charset 时浏览器按 ISO-8859-1 解 UTF-8 → 中文乱码
+# （2026-09-11 用户报障）。未知扩展名的纯文本（log/conf 等）也归入 text/plain 内联展示。
+import mimetypes as _mt
+_ctype = _mt.guess_type(fname)[0] or ''
+if not _ctype:
+    _ext = fname.rsplit('.', 1)[-1].lower() if '.' in fname else ''
+    if _ext in ('txt', 'log', 'md', 'csv', 'conf', 'ini', 'yml', 'yaml',
+                'py', 'js', 'sh', 'sql', 'json'):
+        _ctype = 'text/plain'
+if _ctype.startswith('text/') or _ctype in (
+        'application/json', 'application/javascript',
+        'application/xml', 'image/svg+xml'):
+    _ctype += '; charset=utf-8'
+if _ctype:
+    headers['Content-Type'] = _ctype
+
 return FileResponse(full_path, headers=headers)