calculate sleep time in computed field

[thorinaboenke]

relates to #192

• adds the actual sleep_time as @computed_field and @cached_property to the SleepCommand
  output in attackmate.json:

´´´yaml
commands:

• type: sleep
  seconds: 2

• type: sleep
  seconds: 10
  min_sec: 3
  random: true

• type: sleep
  seconds: 10
  min_sec: 3
  random: true
  ´´´

attackmate.json
{"start-datetime": "2026-01-21T12:56:04.045414", "type": "sleep", "cmd": "sleep", "parameters": {"only_if": null, "error_if": null, "error_if_not": null, "loop_if": null, "loop_if_not": null, "loop_count": "3", "exit_on_error": true, "save": null, "background": false, "kill_on_exit": true, "metadata": null, "min_sec": "0", "seconds": "2", "random": false, "sleep_time": 2}}
{"start-datetime": "2026-01-21T12:56:06.047318", "type": "sleep", "cmd": "sleep", "parameters": {"only_if": null, "error_if": null, "error_if_not": null, "loop_if": null, "loop_if_not": null, "loop_count": "3", "exit_on_error": true, "save": null, "background": false, "kill_on_exit": true, "metadata": null, "min_sec": "3", "seconds": "10", "random": true, "sleep_time": 10}}
{"start-datetime": "2026-01-21T12:56:16.058689", "type": "sleep", "cmd": "sleep", "parameters": {"only_if": null, "error_if": null, "error_if_not": null, "loop_if": null, "loop_if_not": null, "loop_count": "3", "exit_on_error": true, "save": null, "background": false, "kill_on_exit": true, "metadata": null, "min_sec": "3", "seconds": "10", "random": true, "sleep_time": 3}}

attackmate.log:
2026-01-21 12:56:04 INFO - Sleeping 2 seconds
2026-01-21 12:56:06 INFO - Sleeping 10 seconds
2026-01-21 12:56:16 INFO - Sleeping 3 seconds