CI/CD: Duplicate issue detector and auto labelling as "Duplicate"

**Problem**: Contributors must manually search through many existing issues before creating a new one, which is time-consuming and often leads to duplicate reports.

**How**: Add automated duplicate detection using a GitHub bot (semantic matching) and a lightweight GitHub Action to flag similar existing issues on creation.

****Impact**: it will mark that issue duplicate so that maintainer don't have to waste too much time**

Notes: Automation will only suggest possible duplicates (no auto-closing, or auto-closing depends on choice) .

@Zahnentferner what's your view on this? Please assign