Implement Deja evaluation enhancements and benchmark harness

[acoyfellow]

Summary

• add novelty-gated learn merging, hosted hybrid search, token-budgeted inject tiers, entity tag boosting, and asset pointer metadata across Deja runtimes
• expose the new learn/inject request fields through hosted routes, DO methods, and the client surface
• generate a synthetic evaluation dataset plus a runnable harness that writes eval/results.json and eval/RESULTS.md

Testing

• bun test in packages/deja-local
• bun test in packages/deja-edge
• bun test in packages/deja-client
• npx jest test/hosted-memory-quality.test.ts --runInBand
• npm run typecheck
• bun eval/run.ts