fix(workflow): exclude showcase directory from broken link check

Author: kesku

.github/workflows/pr-validation.yml

@@ -30,7 +30,7 @@ jobs:
         run: |
           # Simple check for common broken link patterns
           echo "Checking for potential broken links..."
-          if grep -r "http://localhost\|http://127.0.0.1" docs/; then
+          if grep -r "http://localhost\|http://127.0.0.1" docs/ --exclude-dir=showcase; then
             echo "❌ Found localhost links that should be removed"
             exit 1
           fi