v5.0.8

Changed

• Review skill identity and workflow: skills/review/SKILL.md, README.md, and agents/openai.yaml updated from the old "qa" identity to the new "review" identity. Workflow simplified from 6 steps to 4 steps. Severity scale P0-P3 definition unified.
• Hallucination reference restructured: references/halluciation-review-instruction.md converted from step-by-step process to a reference checklist organized by internal vs. external patterns.
• fix skill README reference: Updated outdated qa reference to review in the list of review report sources.