added username (models.CharField) & searchable (models.BooleanField) to User model in lyric app; new ITs confirm functionality here; dashboard views now ensure that sharing a list w. an email address (as opposed to a username) neither confirms nor denies whether that email address has a registered account (ITs green)

src/apps/lyric/models.py

@@ -24,6 +24,8 @@ class Token(models.Model):
 class User(AbstractBaseUser):
     id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
     email = models.EmailField(unique=True)
+    username = models.CharField(max_length=35, unique=True, null=True, blank=True)
+    searchable = models.BooleanField(default=False)
     is_staff = models.BooleanField(default=False)
     is_superuser = models.BooleanField(default=False)