Improve runCommand timeout diagnostics (process snapshot + output summary)

[olha-ctrl]

• Switched to Start() + Wait() for better timeout observability, it help to capture process exactly when ctx.Done() fires; previous catch on ContextDeadline is too late.
• Set cmd.SysProcAttr.Setpgid = true in execute to avoid overriding in in the runCommand
• Add readable output summary on timeout to get better understanding of last this process was doing (just last line to avoid chunky logs)
• Added: etime (how long the process has been running),wchan (Wait channel) for processTree to log