XY-864: [ELF benchmark vNext P1] Add real-world external adapter comparison contract

[yvette-carlisle]

Summary

• Add a real-world external adapter manifest/report contract with typed coverage states and Docker isolation metadata.
• Add the first memory-project manifest for ELF, qmd, agentmemory, mem0/OpenMemory, claude-mem, memsearch, and OpenViking.
• Update benchmark, comparison, and README docs to distinguish fixture-backed, live-baseline-only, and future live-real-world evidence.

Validation

• cargo make real-world-memory
• cargo make fmt
• cargo make lint-fix
• cargo make checks
• docker compose -f docker-compose.baseline.yml config >/dev/null