📚 Improved backend codebase structure & documentation (#123) 🌟

backend/app.py

@@ -1036,11 +1036,11 @@ def dashboard():
         # Letzte Jobs als Aktivitäten
         recent_jobs = db_session.query(Job).filter(
             Job.user_id == current_user.id if not current_user.is_admin else True
-        ).order_by(Job.updated_at.desc()).limit(5).all()
+        ).order_by(Job.created_at.desc()).limit(5).all()
         
         activities = []
         for job in recent_jobs:
-            time_diff = datetime.now() - (job.updated_at or job.created_at)
+            time_diff = datetime.now() - job.created_at
             if time_diff.days == 0:
                 if time_diff.seconds < 3600:
                     time_str = f"vor {time_diff.seconds // 60} Minuten"
@@ -1745,7 +1745,7 @@ def api_stats():
             today = date.today()
             completed_today = db_session.query(Job).filter(
                 Job.status == 'completed',
-                Job.updated_at >= today
+                Job.created_at >= today
             ).count()
             
             # Online-Drucker (aktive Drucker)