[Bugs] If no `user.email` set an incorrect default `<local user>@github.com` is used instead

**Mood:** 😔
**Category:** Bugs

If no `user.email` is set on a repo (or globally), GH Copilot App appears to have defaulted to `@github.com`. This caused confusion in that my (private) repo began showing GH users as contributors to the project, even though I am the only owner/collaborator. It turns out that my local machine user account name happens to match a (different) GH user.

Granted, setting a Git user name/email should be a first step when cloning a repo, but it's an easy step to forget when setting up a new machine. I feel like GH Copilot App could warn before using a default email.

---
| Field | Value |
| --- | --- |
| App version | 0.2.27 |
| OS | macOS 26.5.1 |
| Theme | Chai |
| Path | /chat |
| Tenure | Week 6 |

Beginne beim /chat-Ablauf und untersuche, wie die App Git user.email abruft, wenn die Repository- und globale Konfiguration nicht gesetzt sind. Reproduziere den Fallback ohne konfigurierte E-Mail und verifiziere anschließend, dass die App warnt, bevor sie @github.com verwendet, anstatt Commits dieser Adresse stillschweigend zuzuschreiben.

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