test: localize calendar recurrence helper import (#4944)

* test: localize calendar recurrence helper import

* test: share calendar route import helper

tests/helpers/calendar_routes.py

@@ -0,0 +1,8 @@
+"""Shared imports for calendar route tests."""
+
+
+def import_calendar_routes():
+    """Import the calendar routes module after test stubs are installed."""
+    import routes.calendar_routes as cal
+
+    return cal