T007: [P] Create Certificate domain entity with validation #44
Description
Phase 2: Foundational
Task: T007
Status: Not Started
Story: Foundational (blocking all user stories)
Parallelizable: Yes - independent from T008-T010
Description
Create Certificate domain entity with all 17 properties, validation rules, state machine, and soft delete support.
Acceptance Criteria
- File created: api/CourseRegistration.Domain/Entities/Certificate.cs
- All 17 properties implemented with proper types and constraints (see data-model.md table)
- CertificateId: Guid (NEWID default, immutable, PK)
- SerialNumber: string (UNIQUE constraint enforced at DB level)
- HolderName: string with validation (Unicode NFC, length 1-120, no control chars)
- Status: enum property with computed logic (Active/Revoked/Expired)
- State transitions documented: Active → Revoked/Expired (terminal states)
- Soft delete flag implemented: IsDeleted bit
- All REQUIRED properties validated in constructor or property setters
- XML documentation on public members
Effort Estimate
4 hours
References
- data-model.md: Certificate Entity section (17 properties listed)
- certificat.instructions.md: Validation Rules
- constitution.md: Principle V (Security, Validation)