new apps.lyric.authenticate model PasswordlessAuthenticationBackend and authenticate() function help determine Token authenticity, login to existing accounts, or create new ones; associated .tests.test_authentication class asserts this functionality; apps.lyric.models & .tests.models now handles token uid instead of id, completing the transition away from email-as-pk

src/apps/lyric/authentication.py

@@ -0,0 +1,16 @@
+from django.core.exceptions import ValidationError
+from .models import Token, User
+
+
+class PasswordlessAuthenticationBackend:
+    def authenticate(self, request, uid=None):
+        if uid is None:
+            return None
+        try:
+            token = Token.objects.get(uid=uid)
+        except (Token.DoesNotExist, ValidationError):
+            return None
+        try:
+            return User.objects.get(email=token.email)
+        except User.DoesNotExist:
+            return User.objects.create(email=token.email)