[WIP] Update logs command to download agentic workflows by default

[Copilot]

• Add --agent-task flag to logs command
• Update getAgenticWorkflowNames to optionally include agent task workflows
• Update listWorkflowRunsWithPagination to accept agent-task parameter
• Update DownloadWorkflowLogs to pass agent-task flag through call chain
• Add tests for agent-task filtering
• Update help text and examples
• Create changeset documenting the change
• Manually test the flag behavior

Original prompt

Reference: https://github.com/githubnext/gh-aw/actions/runs/20700652778/job/59422410369#step:5:1

The "logs" command should only download agentic workflows by default. To also consider the GitHub copilot agent runs, it should have the "--agent-task" flag enabled.

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