docs: explain inversion

src/main/kotlin/com/frcteam3636/frc2025/utils/Inputs.kt

@@ -1,5 +1,6 @@
 package com.frcteam3636.frc2025.utils
 
+import com.frcteam3636.frc2025.Robot
 import edu.wpi.first.math.geometry.Translation2d
 import edu.wpi.first.wpilibj.DriverStation
 import edu.wpi.first.wpilibj.DriverStation.Alliance
@@ -13,7 +14,6 @@ import kotlin.jvm.optionals.getOrNull
 val Joystick.fieldRelativeTranslation2d: Translation2d
     get() {
         val base = translation2d
-        // Joystick x/y are inverted from the standard coordinate system+
         return when (DriverStation.getAlliance().getOrNull()) {
             Alliance.Red -> -base
             else -> base
@@ -23,5 +23,15 @@ val Joystick.fieldRelativeTranslation2d: Translation2d
 /**
  * Returns the translation of the joystick input.
  */
-val Joystick.translation2d: Translation2d // Joystick x/y are inverted from the standard coordinate system
-    get() = Translation2d(-y, -x)
+val Joystick.translation2d: Translation2d
+    // The field-space translation returned by this method is rotated 90 degrees from the joystick's
+    // perspective. (x, y) -> (y, -x) The joystick's Y-axis is also inverted because of our physical
+    // hardware, but this isn't an issue in simulation.
+    get() = Translation2d(
+        if (Robot.model == Robot.Model.SIMULATION) {
+            y
+        } else {
+            -y
+        },
+        -x
+    )