chore: add .claude/ to gitignore

Remove local Claude Code files from tracking.
These are user-specific local configuration files.

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

Author: trend-denny-lee

.claude/ralph-loop.local.md

@@ -94,3 +94,6 @@ $RECYCLE.BIN/
 *.lnk
 
 # End of https://www.toptal.com/developers/gitignore/api/rust,macos,windows,linux
+
+# Claude Code local files
+.claude/