feat: manage agent runner from the cli

[VaibhavAcharya]

Summary

Adds agents command to Netlify CLI for managing AI agent tasks.

Commands

• agents:create - Create and run agent tasks with custom prompts
• agents:list - List agent tasks for a site
• agents:show - View information about a specific agent task
• agents:stop - Stop a running agent task

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[github-actions]

📊 Benchmark results

Comparing with 941ed95

• Dependency count: 1,031 (no change)
• Package size: 284 MB ⬆️ 0.02% increase vs. 941ed95
• Number of ts-expect-error directives: 380 (no change)