docs: document end-to-end benchmark validation

[minixalpha]

Summary

• Document the first end-to-end Terminal-Bench 2.1 validation of the headless CLI, including the Harbor adapter and Docker execution path.
• Record the verified openssl-selfsigned-cert outcome: reward 1.0, 6/6 verifier tests passed, and no agent or verifier exceptions.
• Explain the direct httpx dependency issue and the distinction between text-log tool counts and a structured benchmark trajectory.
• Record the next steps: declare httpx directly, add a reusable Harbor adapter to the project, and build canonical events plus stream-json and trajectory output.
• Regenerate the complete English 0.8.x development notes from the updated Chinese source.

Validation

• Cross-checked the documented reward, verifier results, execution time, and tool-call counts against the saved Harbor artifacts.
• Confirmed the Chinese and English development notes have matching section structure.
• Confirmed the generated English development notes contain no untranslated Chinese text.
• git diff --check main...HEAD

Scope

Documentation only; no runtime behavior changes.