XY-925: [ELF benchmark P1] Expand first-generation OSS continuity and source-store adapters

[yvette-carlisle]

Summary

• Add first-generation OSS real-world fixture coverage for agentmemory, memsearch, and claude-mem.
• Add a repo-native cargo make real-world-first-generation-oss task and benchmark report artifacts.
• Update comparison reports and tests to preserve fixture-backed/live-runtime boundaries, typed blockers, and scenario outcome vocabulary.

Validation

• cargo nextest run -p elf-eval --test real_world_job_benchmark --all-features
• cargo make fmt
• cargo make lint-fix
• cargo make checks
• cargo make real-world-first-generation-oss
• git diff --check