Store the BBB link in the Pool model

apps/participation/models.py

@@ -344,6 +344,15 @@ class Pool(models.Model):
         verbose_name=_("juries"),
     )
 
+    bbb_code = models.CharField(
+        max_length=11,
+        blank=True,
+        default="",
+        verbose_name=_("BigBlueButton code"),
+        help_text=_("The code of the form xxx-xxx-xxx at the end of the BBB link."),
+        validators=[RegexValidator("[a-z]{3}-[a-z]{3}-[a-z]{3}")],
+    )
+
     @property
     def solutions(self):
         return Solution.objects.filter(participation__in=self.participations, final_solution=self.tournament.final)