- Add Certificate + CertificateCategory models with full CRUD API
- Image upload via base64 data URL stored in Text column
- Certificate fields: title, issuer, issue_date, expiry_date, image, description
- Frontend: card grid with category sidebar filter, create/edit dialog
- Include certificates in data backup/export
- Fix hasPhaseParent optimization in GoalDetailPage
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
