Tasks - Convert PRD to JSON Format

Converts a PRD markdown document into the prd.json format for the execution loop.

The Job

1. Read the PRD markdown file
2. Extract tasks (from Tasks section or User Stories)
3. Explode each task into granular, machine-verifiable sub-tasks
4. Order by dependencies (schema → backend → UI → tests)
5. Output to the specified prd.json location

Autonomous mode: Do not ask questions. Use the PRD content and any provided context (branch name, output path) to generate prd.json immediately.

Critical: Agent-Testable Tasks