XY-834: [ELF benchmark P2] Add expanded RAG and graph-memory baseline adapters

[yvette-carlisle]

Summary

• Add research_gate external adapter records for expanded RAG and graph-memory candidates plus deeper qmd/OpenViking profile gates.
• Extend real-world external adapter reporting with execution metadata, source/setup/runtime/resource/retry fields, and research_gate summary counts.
• Update benchmark docs and README comparison language so research gates remain distinct from fixture-backed, live-baseline-only, and live real-world evidence.

Validation

• cargo make fmt
• cargo make lint-fix
• cargo make checks
• cargo make real-world-memory