feat: Add comprehensive feature benchmark suite

New benchmarks for recently added features:
- MERGE operations (mergeNode/mergeEdge with ON CREATE/ON MATCH)
- Property indexes (unique and non-unique)
- Bidirectional queries (both() direction)
- Path finding (shortestPath, paths with maxDepth/maxPaths)
- Feature combinations (real-world ETL scenarios)

Includes:
- 25+ individual benchmarks
- Performance comparisons (MERGE vs manual, both() vs separate)
- Real-world scenario tests (job scraper ETL)
- Detailed reporting with category summaries

🤖 Generated with Claude Code

Co-Authored-By: Claude <noreply@anthropic.com>

Author: michaeloboyle