Move the create-prd workflow into src/core/tasks/bmad-create-prd/ as a
self-contained native skill with SKILL.md, workflow.md, steps-c/, data/,
and templates/. Update all internal path references from absolute
{project-root}/_bmad/... to relative paths. Mark the source
workflow-create-prd.md as standalone:false to prevent duplicate manifest
entries. Update pm.agent.yaml and module-help.csv to use skill:bmad-create-prd.
Alex Verkhovsky