`gh stack submit` fails when remote uses a custom SSH host alias

[EricCrosson]

gh stack submit exits with an error when the git remote URL uses a custom SSH host alias (e.g. github.com-work) instead of the literal github.com hostname. There is no flag to override the repository, so submit is unusable in this configuration.

Steps to reproduce

1. Configure ~/.ssh/config with a host alias (common for multi-account setups):

   Host github.com-work
       HostName github.com
       User git
       IdentityFile ~/.ssh/id_ed25519_work
   

2. Clone using the alias:

   git clone git@github.com-work:org/repo.git
   cd repo
   

   git remote get-url origin → git@github.com-work:org/repo.git

3. Initialize a stack and submit:

   git checkout -b layer-1 && git commit --allow-empty -m "layer 1"
   git checkout -b layer-2 && git commit --allow-empty -m "layer 2"
   git checkout layer-1
   gh stack init --adopt -b main layer-1 layer-2
   gh stack submit --draft
   

Actual result

✗ failed to create GitHub client: determining repository: unable to determine current
repository, none of the git remotes configured for this repository point to a known
GitHub host

The --remote origin flag and GH_HOST=github.com env var do not help — the error
is identical with both.

Expected result

gh stack submit pushes the branches and opens draft PRs, the same as it would with a git@github.com:org/repo.git remote.

What I tried

• gh stack submit --remote origin — same error
• GH_HOST=github.com gh stack submit — same error
• GH_REPO=org/repo gh stack submit — gets past host detection, but then pushes to
  git@github.com:org/repo.git instead of the configured alias, so the push fails
  with a key-agent rejection

Workaround

Push branches manually and create PRs one at a time:

git push origin layer-1 layer-2
gh pr create --draft --repo org/repo --base main   --head layer-1 --title "layer 1"
gh pr create --draft --repo org/repo --base layer-1 --head layer-2 --title "layer 2"

Environment

gh version 2.89.0 (nixpkgs)
gh extension: gh stack (github/gh-stack)
OS: macOS
Remote URL format: git@github.com-<alias>:org/repo.git