fix(web): always drain visit request body to keep keep-alive connections aligned

reaction_board/web/server.py

@@ -323,10 +323,9 @@ border-color:#3a2c22;color:#f3e9dc}button{background:#e9b97c;color:#2a1a10}}
             return
 
         path_value = _param(query, "path", "")
-        if not path_value:
-            body = self._read_small_body()
-            if body:
-                path_value = _json_path(body)
+        body = self._read_small_body()
+        if not path_value and body:
+            path_value = _json_path(body)
 
         user_agent = self.headers.get("User-Agent")
         if not track.count_bots and is_bot(user_agent):
@@ -360,6 +359,8 @@ border-color:#3a2c22;color:#f3e9dc}button{background:#e9b97c;color:#2a1a10}}
         if length <= 0:
             return b""
         if length > VISIT_BODY_LIMIT:
+            # 不读取超长请求体，直接关闭连接，避免 keep-alive 上残留字节错位。
+            self.close_connection = True
             raise ApiError(HTTPStatus.BAD_REQUEST, "bad_request", "请求体过大")
         return self.rfile.read(length)