NAV Fund Services RLS Fixed — Investor Data Now Visible

All nav_ tables (nav_investors, nav_investor_balances, nav_statements, nav_documents, nav_global_funds) were missing public-role RLS policies despite having RLS enabled — causing the anon client to receive zero rows. Added "Allow all operations FOR ALL TO public" policies matching the app-wide convention. Also fixed the SWR isLoading state in the Data Management page so the loading spinner shows correctly during the initial fetch instead of flashing the empty state.