Feat: Editing messages

[zop-hacks]

[6crucified]

opened a PR for this : #346

[Luzivog]

+1 — we want this too. When using Codex in T3 Code, I cannot go back to the last message I sent, edit it, and resend it as I can in the Codex app. Being able to revise at least the most recent user message would be useful.