Fix aircraft weight category classification

- Fixed incorrect category label: 34000-136000kg is Large, not Medium
- Updated JavaScript color matching to properly distinguish categories
- Simplified color logic to use category keywords (light/medium/large/heavy)

This ensures:
- Light aircraft (< 7000kg): Sky blue
- Medium aircraft (7000-34000kg): Green
- Large aircraft (34000-136000kg): Orange
- Heavy aircraft (> 136000kg): Red

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

internal/modes/decoder.go

@@ -789,7 +789,7 @@ func (d *Decoder) getAircraftCategory(tc uint8, ca uint8) string {
 		case 2:
 			return "Medium 7000-34000kg"
 		case 3:
-			return "Medium 34000-136000kg"
+			return "Large 34000-136000kg"
 		case 4:
 			return "High Vortex Large"
 		case 5: