fix: Update pre-commit hook to handle staged deleted files (#11357)

The pre-commit hook was failing when there were staged deleted files
because:
- It was using 'ls' to filter files, which fails when they don't exist
in the filesystem
- Deleted files are still in Git's staging area but not in the
filesystem

Changes made:
1. Added a check to filter files with 'test -f' before passing to
Rubocop
2. Added the same check for staging Rubocop's changes
3. Added '|| true' to prevent errors when no files match the filters

This ensures the pre-commit hook completes successfully even when files
are staged for deletion.

.husky/pre-commit

@@ -4,8 +4,8 @@
 # lint js and vue files
 npx --no-install lint-staged
 
-# lint only staged ruby files
-git diff --name-only --cached | xargs ls -1 2>/dev/null | grep '\.rb$' | xargs bundle exec rubocop --force-exclusion -a
+# lint only staged ruby files that still exist (not deleted)
+git diff --name-only --cached | xargs -I {} sh -c 'test -f "{}" && echo "{}"' | grep '\.rb$' | xargs -I {} bundle exec rubocop --force-exclusion -a "{}" || true
 
 # stage rubocop changes to files
-git diff --name-only --cached | xargs git add
+git diff --name-only --cached | xargs -I {} sh -c 'test -f "{}" && git add "{}"' || true