copilot --continue` resumes the wrong session when multiple repos share the same branch name

[Alan-Jowett]

copilot --continue is selecting sessions from the wrong repository.
It appears to key session selection only on the branch name.

Repro:

1. I have multiple repositories, each with an active Copilot CLI session.

2. All of them happen to use a branch named main.

3. I cd into repo X and run:

   github copilot --continue
   

4. Instead of resuming the session associated with repo X, it resumes a session belonging to repo Y—apparently because both sessions were created while on a branch named main.

Expected behavior:

• Session lookup should prefer repo identity (e.g., full path, git remote, repo ID) over branch name.
• Branch names alone are not unique enough to disambiguate sessions.

Actual behavior:

• Session resolution appears to match on branch name only.
• This causes cross‑repo confusion whenever users have multiple repos with the same branch name—very common, especially for main.

Requested fix:

• Incorporate repository identity into session selection, not just branch name.
• Alternatively, prompt the user when multiple sessions match to let them pick the intended one.

If helpful, I can provide logs or session metadata from affected runs.