Initialize narratio Go module and CLI scaffold

internal/artifacts/s3.go

@@ -0,0 +1,32 @@
+package artifacts
+
+import (
+	"context"
+	"fmt"
+)
+
+// S3Store is a placeholder S3-compatible artifact store.
+type S3Store struct {
+	Bucket string
+	Prefix string
+}
+
+// WriteLocal returns a not-yet-implemented error in the scaffold.
+func (s *S3Store) WriteLocal(_ context.Context, _ Ref, _ []byte) error {
+	return fmt.Errorf("artifacts s3 write local: not yet implemented")
+}
+
+// ReadLocal returns a not-yet-implemented error in the scaffold.
+func (s *S3Store) ReadLocal(_ context.Context, _ Ref) ([]byte, error) {
+	return nil, fmt.Errorf("artifacts s3 read local: not yet implemented")
+}
+
+// ExistsLocal returns a not-yet-implemented error in the scaffold.
+func (s *S3Store) ExistsLocal(_ context.Context, _ Ref) (bool, error) {
+	return false, fmt.Errorf("artifacts s3 exists local: not yet implemented")
+}
+
+// Upload returns a not-yet-implemented error in the scaffold.
+func (s *S3Store) Upload(_ context.Context, _ Ref) (string, error) {
+	return "", fmt.Errorf("artifacts s3 upload: not yet implemented")
+}