feat: added eligibility check to application save method

This commit addresses an issue where users could submit as many applications as they wanted by simply navigating to the previous page and resubmitting the form, therefore bypassing validation that was only existent in the  front end.
Fixes #20.

app/User.php

@@ -121,19 +121,17 @@ class User extends Authenticatable implements MustVerifyEmail
 
 
     public function isEligible(): bool {
-        $eligible = false;
-        $lastApplication = Application::where('applicantUserID', $this->id)->latest()->first();
+        $lastApplication = Application::where('applicantUserID', $this->getAttribute('id'))->latest()->first();
 
         if (is_null($lastApplication)) {
-           $eligible = true;
+            return true;
         }
 
         if ($lastApplication->created_at->diffInMonths(now()) > 1 && in_array($lastApplication->applicationStatus, ['DENIED', 'APPROVED'])) {
-
-            $eligible = true;
+            return true;
         }
 
-        return $eligible;
+        return false;
     }