docs: document token-consumption and retrieval-volume metrics

[tcconnally]

Adds a Metrics section to the README defining token consumption, retrieval volume, and cost-normalized recall as first-class reporting axes alongside accuracy.

Grounded in HiSkill (arXiv:2607.25853): compact, structured, relation-aware context achieved +17.33% success rate while reducing inference token consumption by 78.75% vs the strongest baseline — token efficiency is a decision-relevant benchmark control, not a nice-to-have.

Documentation-only change; no harness behavior modified.

[tcconnally]

/pr-memory-benchmarks-1

Round-2 additions for the metrics PR

The existing token-consumption/retrieval-volume proposal is the right landing point. Please consider adding these bounded controls before merge:

• AgentMemBench as a memory-benchmark arm covering external knowledge, personal QA, and updates.
• SkillEvolBench for frozen-deployment, context-shift, adversarial, and composition controls; skill-library growth is not capability by itself.
• Judge perturbations from 2602.02219, 2603.11027, and 2506.22316: paired reversals, rubric/order canaries, and judge/config hashes.
• Energy-to-Token Production: quality-conditioned tokens and energy fields, with unavailable/estimated values explicit.

The public report should keep prompt/body content out of rows and distinguish measured metrics from estimates.

[tcconnally]

Round-2 research update

Please extend the existing token/retrieval metric PR with: AgentMemBench (2608.00009) and SkillEvolBench (2605.24117) as memory/skill benchmark candidates; judge perturbation and provenance-blindness controls (2602.02219, 2603.11027, 2506.22316, 2508.21164); and energy-to-token reporting (2605.11733). Keep metrics explicit about unavailable telemetry and preserve source/evidence conditions.

Research basis: 2026-08-04 Round 2 synthesis
https://arxiv.org/abs/2605.12981
https://arxiv.org/abs/2607.25853
https://arxiv.org/abs/2606.11632
https://arxiv.org/abs/2607.12650
https://arxiv.org/abs/2606.28690
https://arxiv.org/abs/2607.01919
https://arxiv.org/abs/2601.23132
https://arxiv.org/abs/2604.05969
https://arxiv.org/abs/2604.09378
https://arxiv.org/abs/2603.19974
https://arxiv.org/abs/2605.05274
https://arxiv.org/abs/2602.02219
https://arxiv.org/abs/2603.11027
https://arxiv.org/abs/2406.07791
https://arxiv.org/abs/2506.22316
https://arxiv.org/abs/2508.21164
https://arxiv.org/abs/2605.11733
https://arxiv.org/abs/2608.00783
https://arxiv.org/abs/2608.00009
https://arxiv.org/abs/2605.24117
https://arxiv.org/abs/2608.01619
https://arxiv.org/abs/2608.00426
https://arxiv.org/abs/2604.16838
https://arxiv.org/abs/2606.04193
https://arxiv.org/abs/2105.13116
https://arxiv.org/abs/2510.14133