Copilot CLI enables parallel agent execution

GitHub Copilot CLI has introduced a new feature called `/fleet`, allowing users to run multiple AI agents simultaneously on different files within a codebase. This enhancement enables Copilot to break down complex objectives into independent tasks, dispatching parallel agents to work concurrently. This parallel processing significantly boosts efficiency by avoiding sequential execution, much like a project manager assigning tasks to a team. The orchestrator manages context and coordination, enabling faster and more comprehensive code analysis and modification, improving the developer experience by handling multiple aspects of a task at once.