fix: honor cmd.Env when probing core.sshCommand

Pass the prepared command environment into the SSH config probe so
GIT_CONFIG_* isolation (and any custom Env) is respected when deciding
whether to inject fail-fast GIT_SSH_COMMAND.

Co-authored-by: Ben Schellenberger <bschellenberger2600@users.noreply.github.com>

Author: cursoragent

internal/git/network_env.go

@@ -53,8 +53,8 @@ func repoHasCoreSSHCommand(repoDir string, env []string) bool {
 	if strings.TrimSpace(repoDir) == "" {
 		return false
 	}
-	cmd := exec.Command("git", "-C", repoDir, "config", "--get", "core.sshCommand")
-	cmd.Env = env
-	out, err := cmd.Output()
+	probe := exec.Command("git", "-C", repoDir, "config", "--get", "core.sshCommand")
+	probe.Env = env
+	out, err := probe.Output()
 	return err == nil && strings.TrimSpace(string(out)) != ""
 }