actions: automatically add all opened issues and PRs to project board

[jklare]

• reuse workflow from osism/.github/.github/workflows/add-to-project.yml to add Issues and PRs to project boards

Mirrors osism/release#2483 (6234b559).

[sourcery-ai]

Hey - I've left some high level feedback:

• Consider whether you also want to handle reopened issues/PRs (and possibly edited) in the on: section so that items that are reopened still get added to the project board.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- Consider whether you also want to handle `reopened` issues/PRs (and possibly `edited`) in the `on:` section so that items that are reopened still get added to the project board.

---

Sourcery is free for open source - if you like our reviews please consider sharing them ✨

• X
• Mastodon
• LinkedIn
• Facebook

_{Help me be more useful! Please click 👍 or 👎 on each comment and I'll use the feedback to improve your reviews.}