feat(finance): display transaction reference length as it is restricted to 140 chars

jdav_web/finance/admin.py

@@ -137,6 +137,16 @@ class TransactionOnSubmittedStatementInline(admin.TabularInline):
     }
     readonly_fields = ['text_length_warning']
     extra = 0
+    
+    def text_length_warning(self, obj):
+        """Display reference length, warn if exceeds 140 characters."""
+        len_reference = len(obj.reference)
+        len_string = f"{len_reference}/140"
+        if len_reference > 140:
+            return mark_safe(f'<span style="color: red;">{len_string}</span>')
+        
+        return len_string
+    text_length_warning.short_description = "Länge"
 
     def text_length_warning(self, obj):
         """Display reference length, warn if exceeds 140 characters."""