Remove invalid deprecated flag, clean up backup files

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

.gitignore

@@ -51,3 +51,8 @@ apps/site/.source
 
 # Test artifacts
 test-screenshots
+
+# Backup files
+*.bak
+*.backup
+*~