Add extensive test coverage for the Dolt storage implementation:
- dependencies_extended_test.go: Extended dependency operation tests
- dolt_benchmark_test.go: Performance benchmarks for Dolt operations
- history_test.go: Version history query tests
- labels_test.go: Label operation tests
These tests validate Dolt backend correctness and provide performance
baselines for comparison with SQLite.
Co-authored-by: upstream_syncer <matthew.baker@pihealth.ai>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>