paths.build fix

internal/project/project.go

@@ -788,6 +788,13 @@ func (p *Project) ValidateLayout() error {
 		}
 		info, err := os.Stat(path)
 		if err != nil {
+			// An output dir that does not exist yet is fine: the builder creates
+			// it (MkdirAll) before writing. A bare clone must validate/build from
+			// a clean tree with no pre-step (R2/parity) — only a path that exists
+			// but is NOT a directory is a real error.
+			if errors.Is(err, fs.ErrNotExist) {
+				continue
+			}
 			failures = append(failures, fmt.Errorf("%s: %w", label, err))
 			continue
 		}