ViewScan implementation complete (nodes + relationships)

Features:
- Full YAML-driven graph model (no hardcoded mappings)
- Schema lookup for both nodes and relationships
- Comprehensive testing infrastructure (3 approaches)
- 5/5 tests passing

Changes:
- 6 bug fixes (aliases, columns, CTEs, projections)
- 2 new features (schema lookup, debug logging)
- 3 documentation guides
- 7 test/infrastructure files

Impact: Can now add graph entities via YAML without code changes