Fix exact email grants and clarify cloud and wind labels

tests/test_grant_subscription_by_email.py

@@ -0,0 +1,30 @@
+from scripts.grant_subscription_by_email import _select_exact_user_id
+from src.payments.contract_checkout import PaymentCheckoutError
+
+
+def test_select_exact_user_id_prefers_exact_email_match():
+    payload = {
+        "users": [
+            {"id": "wrong-user", "email": "louischanre+alias@gmail.com"},
+            {"id": "right-user", "email": "louischanre@gmail.com"},
+        ]
+    }
+
+    result = _select_exact_user_id(payload, "louischanre@gmail.com")
+
+    assert result == "right-user"
+
+
+def test_select_exact_user_id_raises_when_exact_email_missing():
+    payload = {
+        "users": [
+            {"id": "wrong-user", "email": "louischanre+alias@gmail.com"},
+        ]
+    }
+
+    try:
+        _select_exact_user_id(payload, "louischanre@gmail.com")
+    except PaymentCheckoutError as exc:
+        assert exc.status_code == 404
+    else:
+        raise AssertionError("expected PaymentCheckoutError")