[FuTseYi]

Purpose

The existing CPU YOLO smoke workflow was manual only, so its checked-in wheat model had never been exercised by GitHub Actions. This PR adds a targeted push trigger on main for changes to actual model assets, the smoke script, and this workflow file, while preserving manual dispatch.

Cost / scope

• A main-branch merge of this PR will trigger the first real CPU inference run and download PyTorch/Ultralytics dependencies. Ordinary README and UI updates won't trigger it.
• Real smoke validates checkpoint load and decoding of one wheat JPEG, not model accuracy or end-to-end Flask/Spring Boot.
• Standard CI must pass before merge. The real CPU run completes separately as a main-branch workflow.