feat: certificate template management and generation (Fasa 7)
- CertificateService: Intervention Image v3 text overlay on template
- GenerateCertificateJob: queued generation with retry logic
- SendCertificateEmailJob: stub (implemented in Fasa 8)
- CertificateTemplateController: upload, config editor, preview, test generate
- Admin/CertificateController: list, generate-all, email-all
- Public/CertificateController: show with questionnaire gate, download
- DejaVuSans fonts bundled under resources/fonts
- Views: admin template/certificate management, public certificate download
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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