Feat: Create 'PM Agent' MVP (Epic -> Ticket Breakdown)

Context

This is the first step in the "Feature Factory" experiment (Epic #7914). We need a "Project Manager" agent that can take a high-level strategic goal (Epic) and break it down into actionable technical tasks (Tickets) for Developer Agents.

Goal

Create a standalone Node.js script ai/agents/pm.mjs that acts as a "Headless PM Agent."

Requirements

1. Input

• The script must accept an Epic Issue Number as a CLI argument: node ai/agents/pm.mjs --epic 123

2. Logic (The "Brain")

• Read: Fetch the Epic title and body using the GitHub MCP tools.
• Context: Query the KnowledgeBase to understand the technical context of the request (e.g., "Add Dark Mode" -> Query "Theming", "CSS variables").
• Plan: Use an LLM (via ai/services.mjs SDK) to break the Epic into 3-5 discrete, implementable steps.
• Format: Ensure each step follows the Protocol defined in ai/agents/PROTOCOL.md (YAML structure, acceptance criteria).

3. Output (Execution)

• Create Issues: The script must autonomously create new GitHub Issues for each step.
• Labeling: Apply the correct labels: agent-task:pending, agent-role:dev, and the ai-generated tag.
• Linking: Post a comment on the original Epic listing the created sub-tickets.

Tech Stack

• Use ai/services.mjs for the AI logic (Code Execution pattern).
• Use commander for CLI parsing.
• Use the github-workflow tools (via SDK import) for issue management.