PRD Validator & Assess Gate — mandatory sections and SMART goals

[DevVig]

Summary
Add a PRD validation step to the Assess phase that fails early if critical sections are missing or weak. Write a docs/analyst/prd-review.md report with actionable fixes. Block backlog generation until PASS.

Why

• Prevents downstream low-quality backlogs and artifacts
• Enforces industry standards before parsing stories

Scope

• Validator module and integration into a2a/cli.py assess
• Report file with checklist scoring and recommendations

Tasks

• Implement a2a/roles/analyst_prd_validator.py with checks for: Summary present; Goals & Success Metrics with SMART metrics; Users & Personas; NFRs covered; Analytics & Rollout Plan; Risks & Dependencies
• Score sections and identify gaps; produce docs/analyst/prd-review.md
• Fail the assess pipeline (return non-zero) when below threshold; print friendly guidance with @analyst prd-wizard link
• Add config to .a2dev/policies/assess.yaml for required sections and thresholds
• Update status line and timeline with validator results

Acceptance Criteria

• Missing or weak PRD sections produce FAIL with clear remediation
• Backlog generation is skipped until PRD passes validation
• Cyon PRD (generic sample) is flagged with specific recommendations

References

• Cyon docs/PRD.md (example of poor PRD)
• .a2dev/templates/prd.md (strong baseline)