snapshot: preserve audit log and filtering phase

backend/workflows/models.py

@@ -1,3 +1,4 @@
+from django.conf import settings
 from django.db import models
 from django.utils.translation import get_language
 
@@ -22,6 +23,32 @@ class EmployeeProfile(models.Model):
         return f"{self.full_name} <{self.work_email}>"
 
 
+class AdminAuditLog(models.Model):
+    actor = models.ForeignKey(
+        settings.AUTH_USER_MODEL,
+        null=True,
+        blank=True,
+        on_delete=models.SET_NULL,
+        related_name='admin_audit_logs',
+    )
+    actor_display = models.CharField(max_length=255, blank=True)
+    action = models.CharField(max_length=120)
+    target_type = models.CharField(max_length=80, blank=True)
+    target_id = models.PositiveIntegerField(null=True, blank=True)
+    target_label = models.CharField(max_length=255, blank=True)
+    details = models.JSONField(default=dict, blank=True)
+    created_at = models.DateTimeField(auto_now_add=True)
+
+    class Meta:
+        ordering = ['-created_at', '-id']
+        verbose_name = 'Admin Audit Log'
+        verbose_name_plural = 'Admin Audit Logs'
+
+    def __str__(self) -> str:
+        actor = self.actor_display or 'Unbekannt'
+        return f'{self.created_at:%Y-%m-%d %H:%M} | {actor} | {self.action}'
+
+
 class OnboardingRequest(models.Model):
     full_name = models.CharField(max_length=255, verbose_name='Vorname und Nachname')
     gender = models.CharField(