feat(library): add class filtering and sorting to library loans admin view

- Add class filter dropdown and class column to borrowings table
- Implement interactive client-side column sorting for tables
- Update backend route to resolve and map user class information

Web/app.py

@@ -3314,7 +3314,7 @@ def library_loans_admin():
     if 'username' not in session:
         flash('Ihnen ist es nicht gestattet auf dieser Internetanwendung, die eben besuchte Adrrese zu nutzen, versuchen sie es erneut nach dem sie sich mit einem berechtigten Nutzer angemeldet haben!', 'error')
         return redirect(url_for('login'))
-    
+
     current_permissions = us.get_effective_permissions(session['username'])
 
     if not current_permissions['pages'].get('library_loans_admin', False):
@@ -3342,10 +3342,12 @@ def library_loans_admin():
         db = client[MONGODB_DB]
         items_col = db['items']
         ausleihungen_col = db['ausleihungen']
+        users_col = db['users']
 
         library_items = list(items_col.find(
             {'ItemType': {'$in': LIBRARY_ITEM_TYPES}, 'Deleted': {'$ne': True}},
-            {'Name': 1, 'Code_4': 1, 'Anschaffungskosten': 1, 'Condition': 1, 'HasDamage': 1, 'DamageReports': 1, 'Verfuegbar': 1, 'User': 1, 'ItemType': 1, 'Author': 1, 'ISBN': 1}
+            {'Name': 1, 'Code_4': 1, 'Anschaffungskosten': 1, 'Condition': 1, 'HasDamage': 1, 'DamageReports': 1,
+             'Verfuegbar': 1, 'User': 1, 'ItemType': 1, 'Author': 1, 'ISBN': 1}
         ))
         item_map = {str(item['_id']): item for item in library_items if item.get('_id')}
         item_ids = list(item_map.keys())
@@ -3354,28 +3356,68 @@ def library_loans_admin():
         if item_ids:
             active_records = list(ausleihungen_col.find(
                 {'Item': {'$in': item_ids}, 'Status': {'$in': ['active', 'planned', 'completed']}},
-                {'User': 1, 'Item': 1, 'Status': 1, 'Start': 1, 'End': 1, 'Period': 1, 'Notes': 1, 'InvoiceData': 1}
+                {'User': 1, 'Item': 1, 'Status': 1, 'Start': 1, 'End': 1, 'Period': 1, 'Notes': 1, 'InvoiceData': 1,
+                 'Klasse': 1, 'Class': 1, 'school_class': 1}
             ).sort('Start', -1))
 
+        user_map = {}
+        if active_records:
+            raw_users = list({r.get('User') for r in active_records if r.get('User')})
+            decrypted_users = []
+            for ru in raw_users:
+                try:
+                    du = decrypt_text(ru) if ru else ''
+                    if du:
+                        decrypted_users.append(du)
+                except Exception:
+                    pass
+
+            query_identifiers = list(set(raw_users + decrypted_users))
+            if query_identifiers:
+                user_docs = list(users_col.find(
+                    {'$or': [
+                        {'Username': {'$in': query_identifiers}},
+                        {'Name': {'$in': query_identifiers}},
+                        {'User': {'$in': query_identifiers}}
+                    ]},
+                    {'Username': 1, 'Name': 1, 'User': 1, 'Klasse': 1, 'Class': 1, 'school_class': 1}
+                ))
+                for u in user_docs:
+                    cls = u.get('Klasse') or u.get('Class') or u.get('school_class') or ''
+                    if cls:
+                        if u.get('Username'): user_map[u['Username']] = cls
+                        if u.get('Name'): user_map[u['Name']] = cls
+                        if u.get('User'): user_map[u['User']] = cls
+
         active_item_ids = set()
         loan_entries = []
         for record in active_records:
             item_id = str(record.get('Item') or '')
-            item_doc = item_map.get(item_id)
             if item_id and record.get('Status') == 'active':
                 active_item_ids.add(item_id)
 
+            item_doc = item_map.get(item_id)
             if not item_doc:
                 continue
 
             invoice_data = record.get('InvoiceData') or {}
             condition_value = str(item_doc.get('Condition', '')).strip().lower()
-            item_has_damage = bool(item_doc.get('HasDamage')) or condition_value == 'destroyed' or bool(item_doc.get('DamageReports'))
+            item_has_damage = bool(item_doc.get('HasDamage')) or condition_value == 'destroyed' or bool(
+                item_doc.get('DamageReports'))
             damage_reports = item_doc.get('DamageReports', []) or []
 
             raw_user = record.get('User', '')
             decrypted_user = decrypt_text(raw_user) if raw_user else ''
 
+            user_class = (
+                    record.get('Klasse')
+                    or record.get('Class')
+                    or record.get('school_class')
+                    or user_map.get(raw_user, '')
+                    or user_map.get(decrypted_user, '')
+                    or ''
+            )
+
             loan_entries.append({
                 'id': str(record.get('_id')),
                 'item_id': item_id,
@@ -3384,7 +3426,8 @@ def library_loans_admin():
                 'item_author': item_doc.get('Author', ''),
                 'item_isbn': item_doc.get('ISBN', ''),
                 'item_cost_raw': item_doc.get('Anschaffungskosten', ''),
-                'user': decrypted_user, 
+                'user': decrypted_user,
+                'klasse': user_class,
                 'status': record.get('Status', ''),
                 'start': fmt_dt(record.get('Start')),
                 'end': fmt_dt(record.get('End')),