- Added new board definition: `boards/gat562_mesh_trial_tracker.json` for the GAT562 Mesh Trial Tracker, based on the nRF52840 architecture.
- Created `variants/gat562_mesh_trial_tracker/` directory with `platformio.ini` environment for building firmware for this board.
- Board configuration is based on the RAK4631, as the GAT562 uses the same GPIO and SSD1306 display setup.
- Updated build flags and library dependencies for the new board.
This change enables Meshtastic firmware development and deployment for the GAT-IOT GAT562 Mesh Trial Tracker, expanding hardware compatibility.
