refactor(api): add IssueRepoInfo for minimal issue repo queries

Add a new IssueRepoInfo function that fetches only the fields needed
for issue creation (id, name, owner, hasIssuesEnabled, viewerPermission),
avoiding defaultBranchRef and other fields that require Contents:Read.

Also add StubIssueRepoInfoResponse helper to httpmock for testing.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

api/queries_repo.go

@@ -314,6 +314,44 @@ func FetchRepository(client *Client, repo ghrepo.Interface, fields []string) (*R
 	return InitRepoHostname(result.Repository, repo.RepoHost()), nil
 }
 
+// IssueRepoInfo fetches only the repository fields needed for issue creation,
+// avoiding fields like defaultBranchRef that require additional token permissions.
+func IssueRepoInfo(client *Client, repo ghrepo.Interface) (*Repository, error) {
+	query := `
+	query IssueRepositoryInfo($owner: String!, $name: String!) {
+		repository(owner: $owner, name: $name) {
+			id
+			name
+			owner { login }
+			hasIssuesEnabled
+			viewerPermission
+		}
+	}`
+	variables := map[string]interface{}{
+		"owner": repo.RepoOwner(),
+		"name":  repo.RepoName(),
+	}
+
+	var result struct {
+		Repository *Repository
+	}
+	if err := client.GraphQL(repo.RepoHost(), query, variables, &result); err != nil {
+		return nil, err
+	}
+	if result.Repository == nil {
+		return nil, GraphQLError{
+			GraphQLError: &ghAPI.GraphQLError{
+				Errors: []ghAPI.GraphQLErrorItem{{
+					Type:    "NOT_FOUND",
+					Message: fmt.Sprintf("Could not resolve to a Repository with the name '%s/%s'.", repo.RepoOwner(), repo.RepoName()),
+				}},
+			},
+		}
+	}
+
+	return InitRepoHostname(result.Repository, repo.RepoHost()), nil
+}
+
 func GitHubRepo(client *Client, repo ghrepo.Interface) (*Repository, error) {
 	query := `
 	fragment repo on Repository {

pkg/httpmock/legacy.go

@@ -22,6 +22,20 @@ func (r *Registry) StubRepoInfoResponse(owner, repo, branch string) {
 		`, repo, owner, branch)))
 }
 
+func (r *Registry) StubIssueRepoInfoResponse(owner, repo string) {
+	r.Register(
+		GraphQL(`query IssueRepositoryInfo\b`),
+		StringResponse(fmt.Sprintf(`
+		{ "data": { "repository": {
+			"id": "REPOID",
+			"name": "%s",
+			"owner": {"login": "%s"},
+			"hasIssuesEnabled": true,
+			"viewerPermission": "WRITE"
+		} } }
+		`, repo, owner)))
+}
+
 func (r *Registry) StubRepoResponse(owner, repo string) {
 	r.StubRepoResponseWithPermission(owner, repo, "WRITE")
 }