fork of prime agent with changes i want but are not upstreamable probqbly (and some fixes)

Support /fast with OpenAI API-key authentication (#1609) master

* feat(coding-agent): support /fast with OpenAI API-key authentication (ENG-5425) Widens supportsFastMode() to admit GPT-5.4/GPT-5.5/GPT-5.6 on the openai provider (openai-responses API) in addition to ChatGPT auth, corrects the GPT-5.6 fast-pricing multiplier from 2.5x to 2x per OpenAI's current pricing table, and updates the /fast unavailable message. Resolves discussion #1595. * docs(ai): trim pricing comments to source reference only * chore: drop research scratch file from the branch * chore: restore package-lock.json from main (unrelated npm churn) * test: update fast-mode unavailable message assertion