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/Libraries/phpunit.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:noNamespaceSchemaLocation="../../vendor/phpunit/phpunit/phpunit.xsd"
+    bootstrap="../../vendor/autoload.php"
+    colors="true"
+    cacheDirectory="../../.phpunit.cache">
+    <testsuites>
+        <testsuite name="Libraries">
+            <directory suffix="Test.php">.</directory>
+        </testsuite>
+    </testsuites>
+</phpunit>