Add Shape expressions validation and quality reporting to GitHub Actions

[marvinm2]

Extend the existing weekly GitHub Actions pipeline to include comprehensive data quality validation and reporting.

Implementation Plan

Shape Expressions Validation

• Add ShEx/SHACL validation to the weekly data generation pipeline (Saturday 08:00 UTC)
• Validate RDF structure, data completeness, and consistency
• Check reference integrity and identifier resolution

Quality Metrics to Generate

• Coverage metrics: AOPs, Key Events, Key Event Relationships, Chemical Stressors
• Data completeness: Missing properties, empty values, required fields
• Consistency checks: Duplicate entities, conflicting data, invalid references
• Data freshness: Last update timestamps, source data age
• Reference integrity: Broken external links, missing identifiers (HGNC, ChEBI, etc.)

Output Format

• Generate quality-report.json alongside existing RDF files
• Include summary statistics, detailed validation results, and trend data
• Export as static files for consumption by SNORQL interface

Integration Points

• Leverage existing data pipeline infrastructure
• Add quality gates to prevent deployment of poor-quality data
• Coordinate with aopwiki-snorql-extended repo for quality dashboard display

Cross-Repository Coordination

This issue coordinates with the SNORQL interface repository to create a comprehensive data quality solution. The SNORQL side will display the quality reports generated here.

Related: Will create corresponding issue in aopwiki-snorql-extended for the display interface.