pkp#10051 Fixed HTML entity code & in OJS email subject (pkp#10052)

* pkp#10051 Fixed display & in email subjects to show correctly
* pkp#10051 Decode HTML entities in email subject during parameter replacement

classes/mail/MailTemplate.inc.php

@@ -216,7 +216,7 @@ function send() {
 	}
 
 	/**
-	 * Replace template variables in the message body.
+	 * Replace template variables in the message body and subject.
 	 * @param $params array Parameters to assign (augments anything provided via setParams)
 	 */
 	function replaceParams() {
@@ -231,9 +231,11 @@ function replaceParams() {
 					$body = str_replace('{$' . $key . '}', $value, $body);
 				}
 			}
-
 			$subject = str_replace('{$' . $key . '}', $value, $subject);
 		}
+
+		// Decode HTML entities for the subject after all replacements
+		$subject = htmlspecialchars_decode($subject, ENT_QUOTES | ENT_HTML5);
 		$this->setSubject($subject);
 		$this->setBody($body);
 	}