docs: refresh 指令消费 screenshots from demo console

Replace KAFKA, ROCKETMQ, RABBITMQ, PULSAR, and NACOS command consumer
images with captures from http://demo.fluxmq.com/#/instruct/index (current
UI: 新增, type picker, configuration modal). Remove unused *_cmd_3 assets for
types that only document two steps.

Made-with: Cursor

Author: 1ssqq1lxr