fix: suppress Codex commentary stream deltas

[davidojedalopez]

Summary

• suppress live streaming of Codex Responses commentary / analysis message-item deltas
• keep those deltas in collected output_text / transcript state for internal handling
• add regression coverage proving commentary before tool calls is not streamed while final_answer still streams

Why

Codex can emit a commentary-phase message immediately before a function call in the same Responses stream. Hermes was treating the response.output_text.delta as user-facing stream content, so gateway platforms like Telegram could receive model planning/todo text before final-send suppression kicked in.

[alt-glitch]

This was generated by AI during triage.

Duplicate of #25268 — same Codex Responses commentary stream-delta suppression mechanism, both targeting #24933. #25268 is the more comprehensive open fix (suppresses both the commentary message-item promotion and the matching response.output_text.delta stream events). Competing/complementary open cluster for #24933: #21568 (earliest, callback sanitize), #26898 (draft), #41343 (routes commentary to reasoning channel). Maintainer to pick the canonical fix.

[davidojedalopez]

Closing per David's review; work will remain local.