maven: fix test mocks for CalendarEvents interface (verification)

- Add CalendarEvents method to recordingAPI in auth_test.go
- Add CalendarEvents method to fakeCore in handlers_test.go

Co-Authored-By: opencode <opencode@anthropic.com>

internal/loop/loop.go

@@ -134,4 +134,4 @@ func CooldownFor(base time.Duration, lastSend time.Time) time.Time {
 		return time.Time{} // never sent → no cooldown active
 	}
 	return lastSend.Add(base)
-}
+}