Fix Token_lib::render() for PHP 8.4 compatibility

- Replaced deprecated strftime() with IntlDateFormatter
- Added proper handling for edge cases:
  - Strings with '%' not in date format (e.g., 'Discount: 50%')
  - Invalid date formats (e.g., '%-%-%', '%Y-%q-%bad')
  - Very long strings
- Added comprehensive unit tests for Token_lib
- All date format specifiers now mapped to IntlDateFormatter patterns

tests/phpunit.xml

@@ -10,6 +10,9 @@
     <testsuite name="Helpers">
         <directory>helpers</directory>
     </testsuite>
+    <testsuite name="Libraries">
+        <directory>Libraries</directory>
+    </testsuite>
 </testsuites>
 
 </phpunit>