gitadora: (arena model) fix j32d encoding & use velocity (#483)

## Link to GitHub Issue, if one exists
N/A

## Description of change
in current implementation j32d analog values are not encoded properly,
values are supposed to go up to 1023, but they show up as 771 in game

## Testing
tested with M32-007-2025092400, used DM PAD CALIBRATION menu

src/spice2x/games/gitadora/j32d.h

@@ -22,4 +22,4 @@ namespace games::gitadora {
                 uint8_t pedals;
             };
         };
-}
+}