Add .claude and CLAUDE.md to .Rbuildignore

Exclude Claude Code configuration files from package builds
to avoid NOTEs during R CMD check.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: mountainMath

.Rbuildignore

@@ -21,3 +21,5 @@ fix_meta.sh
 ^CRAN-SUBMISSION$
 ^\.github$
 R-CMD-check-old.yaml
+^\.claude$
+^CLAUDE\.md$