Extracted systemMonitorMachine to handle background system monitoring tasks. This machine runs alongside the player machine and handles periodic updates like fetching flight plans and refreshing system data.

Added last profit tracking for ships - each ship now saves its most recent trade profit for quick reference. Improved request caching in the ship requests view with better display of cached vs fresh requests.

Fixed several ship state issues: properly expire flight plans when they complete, resolve stale ship locations by triggering a getShip call, and handle cases where ships have no flight plan or location. The trade route determination was also fixed to handle edge cases better.

Removed the old trade component and cleaned up debug code. Various buy and upgrade flow fixes.