Stop requesting the user email from the OIDC provider

OIDCConfig now asks for the openid and profile scopes only: kaya-oidc's
default would also request email, which the platform never stores or
exposes. The display-name fallback drops the email claim too
(preferred_username, name, then the sub).

Tests pin the configured scopes and cover an IdP that still returns an
email claim: the claim is ignored and absent from /api/me.

server/packages/tavolo-platform/tests/test_auth.py

@@ -106,9 +106,11 @@ class DisplayNameTest(unittest.TestCase):
         user = OIDCUser({"sub": "alice", "name": "Alice"})
         self.assertEqual("Alice", display_name(user))
 
-    def test_falls_back_to_email(self) -> None:
+    def test_ignores_email(self) -> None:
+        # The app requests only the openid and profile scopes; an email
+        # claim the provider still returns must not leak into the name.
         user = OIDCUser({"sub": "alice", "email": "alice@example.com"})
-        self.assertEqual("alice@example.com", display_name(user))
+        self.assertEqual("alice", display_name(user))
 
     def test_falls_back_to_sub(self) -> None:
         user = OIDCUser({"sub": "alice"})