feat: harmonize mailbox messages

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

lib/Client/Mailbox.php

@@ -22,6 +22,8 @@ final class Mailbox
         private readonly int $recent = 0,
         private readonly array $flags = [],
         private readonly bool $readOnly = true,
+        private readonly ?int $uidNext = null,
+        private readonly ?int $highestModSeq = null,
     ) {}
 
     public function fromStatus(MailboxStatusResult $status): self
@@ -38,6 +40,8 @@ final class Mailbox
             $this->recent,
             $this->flags,
             $this->readOnly,
+            $items['UIDNEXT'] ?? $this->uidNext,
+            $items['HIGHESTMODSEQ'] ?? $this->highestModSeq,
         );
     }
 
@@ -64,6 +68,16 @@ final class Mailbox
         return $this->uidValidity;
     }
 
+    public function uidNext(): ?int
+    {
+        return $this->uidNext;
+    }
+
+    public function highestModSeq(): ?int
+    {
+        return $this->highestModSeq;
+    }
+
     public function messages(): int
     {
         return $this->messages;