Issue #184 - Add investigation:Technician role class

[vulnmaster]

Adds investigation:Technician as a new role class to the CASE investigation ontology, addressing Issue #184.

A technician is a forensics role focused on technical tasks during investigations, such as evidence collection, preservation, processing, initial analysis, and repair.

Changes:

• Added investigation:Technician class definition to investigation.ttl
• Created comprehensive test example (technician_role_PASS.json) demonstrating Identity-role-performer pattern with temporal tracking
• Updated test suite (Makefile and test_validation.py)
• Updated ChangeLog

The implementation follows the established pattern used by other role classes (Attorney, Examiner, Investigator, Subject) and maintains backward compatibility.

Tests demonstrate:

• Technician role instances with appointment dates (startTime)
• Identity linked to Technician role via uco-core:role
• Technician role as performer of InvestigativeAction
• Integration with Investigation, File, and ProvenanceRecord

All SHACL validation tests pass.

This is a low risk addition to CASE.

Ready for solution review.