This skill should be used when the user says "execute plan", "run the plan", "start execution", "execute project", "execute all tasks", "run all tasks", "run plan in parallel", "execute with review gates", or wants to execute a full structured project plan after tasks have been created via arn-code-taskify. This skill runs ALL tasks from the task list — for executing a single specific task, use arn-code-execute-task instead. For Agent Teams mode, use arn-code-execute-plan-teams. Do NOT use this skill when executing a single task — use `/arn-code-execute-task` instead.