DONE: fix naming, add transaction for completion of membership application (#12)

Co-authored-by: ISMAIL MASSERAN <topaz@ISMAILs-Macbook.local>
Reviewed-on: #12

be/Modules/MembershipApplication/Entities/MembershipApplicationReview.php

@@ -69,4 +69,13 @@ class MembershipApplicationReview extends Model
 
         return BoardDecision::tryFrom($this->decision);
     }
+
+    public function completionDecision(): ?BoardDecision
+    {
+        if ($this->stage !== ReviewStage::Completion) {
+            return null;
+        }
+
+        return BoardDecision::tryFrom($this->decision);
+    }
 }