feat: mail entity download

Signed-off-by: Sebastian Krupinski <krupinski01@gmail.com>

shared/lib/Mail/Service/ServiceBaseInterface.php

@@ -12,6 +12,7 @@ namespace KTXF\Mail\Service;
 use Generator;
 use KTXF\Mail\Collection\CollectionBaseInterface;
 use KTXF\Mail\Object\AddressInterface;
+use KTXF\Resource\BinaryResource;
 use KTXF\Resource\Delta\Delta;
 use KTXF\Resource\Filter\IFilter;
 use KTXF\Resource\Identifier\EntityIdentifierInterface;
@@ -251,7 +252,7 @@ interface ServiceBaseInterface extends ResourceServiceBaseInterface {
      */
     public function entityFetchBulk(EntityIdentifierInterface ...$identifiers): array;
 
-        /**
+    /**
      * Fetches one or more entities
      *
      * @since 2025.05.01
@@ -262,4 +263,16 @@ interface ServiceBaseInterface extends ResourceServiceBaseInterface {
      */
     public function entityFetchStream(EntityIdentifierInterface ...$identifiers): Generator;
 
+
+    /**
+     * Downloads a message or part of a message
+     *
+     * @since 2025.05.01
+     *
+     * @param EntityIdentifierInterface $target Message identifier
+     * @param array|null $part Optional part to download
+     *
+     * @return BinaryResource
+     */
+    public function entityDownload(EntityIdentifierInterface $target, array|null $part): BinaryResource;
 }