- Add vessel fields to TheaterPostureSummary type (destroyers, frigates,
carriers, submarines, patrol, auxiliaryVessels, totalVessels)
- Update API to return theater bounds for client-side vessel matching
- Panel fetches vessels client-side (AIS WebSocket) and merges with
server-side aircraft data (OpenSky API)
- Display shows AIR and NAVAL sections when vessels detected
- Add posture-section-label CSS for section headers