Add logic to include active trainers as newsletter recipients

- Enhanced the getRecipientsByGroup function to filter and add active trainers from users.json to the newsletter recipients list.
- Ensured that duplicate emails are not added to the recipients array.

server/utils/newsletter.js

@@ -236,6 +236,22 @@ export async function getRecipientsByGroup(targetGroup) {
           email: m.email,
           name: `${m.firstName || ''} ${m.lastName || ''}`.trim() || m.name || ''
         }))
+
+      // Zusätzlich aktive Trainer aus users.json anschreiben
+      users
+        .filter(u => {
+          if (!u.active || !u.email || !u.email.trim()) return false
+          const roles = Array.isArray(u.roles) ? u.roles : (u.role ? [u.role] : [])
+          return roles.includes('trainer')
+        })
+        .forEach(u => {
+          if (!recipients.find(r => r.email.toLowerCase().trim() === u.email.toLowerCase().trim())) {
+            recipients.push({
+              email: u.email.trim(),
+              name: u.name || ''
+            })
+          }
+        })
       break
 
     case 'mannschaftsspieler':