refactor: remove VesselRegistrationHeadDashboardPage and associated navigation links

apps/backoffice/src/app/features/vessel-registration-head/pages/VesselRegistrationHeadDashboardPage.tsx

@@ -1,21 +0,0 @@
-import { Container } from '@mantine/core';
-import { FeatureUnavailable } from '@ema-platform/ui';
-
-/**
- * Placeholder until this feature has a backend.
- *
- * This page previously rendered hardcoded sample records, which were
- * indistinguishable from real ones.
- */
-export function VesselRegistrationHeadDashboardPage() {
-  return (
-    <Container size="lg" py="xl">
-      <FeatureUnavailable
-        title="Vessel registration overview"
-        description="Vessel registration is not connected to the backend yet, so there are no figures to report."
-      />
-    </Container>
-  );
-}
-
-export default VesselRegistrationHeadDashboardPage;