reenabled admin area; outfitted apps.lyric.models w. AbstractBaseUser instead of custom user class; many other fns & several models updated to accomodate, such as set_unusable_password() method to base user model; reset staging db to prepare for refreshed lyric migrations to accomodate for retrofitted pw field

src/core/settings.py

@@ -39,7 +39,7 @@ else:
 
 INSTALLED_APPS = [
     # Django apps
-    # 'django.contrib.admin',
+    'django.contrib.admin',
     'django.contrib.auth',
     'django.contrib.contenttypes',
     'django.contrib.sessions',
@@ -123,6 +123,7 @@ AUTH_PASSWORD_VALIDATORS = [
 AUTH_USER_MODEL = "lyric.User"
 
 AUTHENTICATION_BACKENDS = [
+    "django.contrib.auth.backends.ModelBackend",
     "apps.lyric.authentication.PasswordlessAuthenticationBackend",
 ]