Add a new stop command that allows users to gracefully stop running tasks and clean up associated resources including Docker containers, Git worktrees, and branches.

The command provides granular control over what resources to clean up through options, making it flexible for different use cases while providing a sensible default behavior.

Changes

• New stop command: Added rover stop <taskId> command with comprehensive cleanup options
• Resource cleanup: Supports stopping Docker containers, removing Git worktrees, and deleting branches
• Flexible options: Added --remove-all, --remove-container, and --remove-git-worktree-and-branch flags
• JSON output support: Added --json option for programmatic usage
• Telemetry integration: Added stop task event tracking to telemetry package
• Error handling: Proper error handling for missing tasks and cleanup failures
• User feedback: Clear success messages and helpful tips for next steps

Notes

The stop command integrates with the existing task lifecycle by updating the task status to "cancelled" and providing users with helpful next steps like viewing logs, restarting, or completely deleting the task.

Closes: #78