fix: check Close() error after io.Copy to writable files

cmd/picoclaw/internal/skills/helpers.go

@@ -345,9 +345,11 @@ func copyDirectory(src, dst string) error {
 		if err != nil {
 			return err
 		}
-		defer dstFile.Close()
 
-		_, err = io.Copy(dstFile, srcFile)
-		return err
+		_, copyErr := io.Copy(dstFile, srcFile)
+		if closeErr := dstFile.Close(); closeErr != nil && copyErr == nil {
+			return fmt.Errorf("close destination file %s: %w", dstPath, closeErr)
+		}
+		return copyErr
 	})
 }