Remove prompt files, pushed only to origin. On branch edburns/dd-3012834-experimental-annotation

deleted:    dd-3012834-remove-before-merge/20260606-prompts.md
deleted:    dd-3012834-remove-before-merge/dd-3012835-plan-to-implement-CopilotExperimental.md
deleted:    dd-3012834-remove-before-merge/dd-3012835-sketch.md

Author: edburns