fix(repo): do not forward unsupported --repo to repo fork

[bauti-defi]

In gh-axi 0.1.34, repo fork inherits non-git repository context through generic ghExec, appending unsupported --repo owner/name to native gh repo fork.

Two independent hermetic validations confirmed:

GH_REPO=bauti-defi/oh-omp gh-axi repo fork can1357/oh-my-pi --clone --remote

forwards gh repo fork can1357/oh-my-pi --clone --remote --repo bauti-defi/oh-omp, which native gh rejects before any fork request.

Do not append --repo to native gh repo fork; retain the explicit positional target or reject conflicting context before delegation.

[kunchenguid]

Speaking as Kun's firstmate: this is a real bug on latest main (0.1.34, 84112b7).

VISION.md:

• Scope: aligns. This is existing gh repo fork wrapping, not new GitHub capability.
• Interface: aligns. Forwarding a flag native gh rejects is not agent-ergonomic.

Evidence: forkRepo calls ghExec(ghArgs, ctx). buildArgs appends --repo <nwo> for flag/env context (src/gh.ts). edit/view/clone already avoid passing ctx; fork does not. Native gh repo fork does not accept --repo.

Labeling ready-for-pr.