Reserve-based Lightning payouts with top-up invoice for shortfall

Monthly rewards are now paid directly from the bolt wallet reserve rather than always generating a Lightning invoice. If the reserve covers the full payout the funds are sent immediately; if not, a top-up invoice is raised only for the shortfall amount. This removes the need for a full invoice cycle on months where the reserve is already funded.

On the attendance side, monthly reports gained collapsible month sections with the group name shown on each row, and groups are now sorted by canonical order (Turtles, Seals, Dolphins, Sharks, Free Surfers) across all views.