fix: properly configure .gitignore to exclude node_modules and test artifacts

Author: claude

.gitignore

@@ -1,5 +1,7 @@
 /.DS_Store
 /DATA-PERSISTENCE-GUIDE.md
-/ICON_INSTRUCTIONS.mdcoverage/
+/ICON_INSTRUCTIONS.md
+node_modules/
+coverage/
 html/
 .vitest/