Add hold-to-sprint with dedicated speed multiplier

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Assets/Scripts/PlayerCharacterController.cs

@@ -32,6 +32,9 @@ public class PlayerCharacterController : MonoBehaviour
     [Tooltip("Horizontal movement speed (units/second).")]
     public float moveSpeed = 4f;
 
+    [Tooltip("Speed multiplier applied to ground movement while the sprint key (Left Shift) is held.")]
+    public float sprintSpeedMultiplier = 1.8f;
+
     [Tooltip("Interpret WASD relative to the camera (off = world X/Z axes).")]
     public bool cameraRelative = true;
 
@@ -165,6 +168,7 @@ public class PlayerCharacterController : MonoBehaviour
     {
         float h = 0f, v = 0f;
         bool jumpPressed = false;
+        bool sprinting = false;
 
         // Skip input when control is disabled (e.g. paint mode); gravity and
         // grounding below still run so the player stays planted.
@@ -179,11 +183,13 @@ public class PlayerCharacterController : MonoBehaviour
                 if (keyboard.sKey.isPressed) v -= 1f;
                 if (keyboard.wKey.isPressed) v += 1f;
                 jumpPressed = keyboard.spaceKey.wasPressedThisFrame;
+                sprinting = keyboard.leftShiftKey.isPressed;
             }
 #else
             h = Input.GetAxisRaw("Horizontal");
             v = Input.GetAxisRaw("Vertical");
             jumpPressed = Input.GetButtonDown("Jump");
+            sprinting = Input.GetKey(KeyCode.LeftShift);
 #endif
         }
 
@@ -265,7 +271,8 @@ public class PlayerCharacterController : MonoBehaviour
             _slideSpeed = 0f;
         }
 
-        Vector3 velocity = moveDir * moveSpeed + slideVelocity + Vector3.up * _verticalVelocity;
+        float currentSpeed = sprinting ? moveSpeed * sprintSpeedMultiplier : moveSpeed;
+        Vector3 velocity = moveDir * currentSpeed + slideVelocity + Vector3.up * _verticalVelocity;
 
         // Move fires OnControllerColliderHit, which refills the ground normal;
         // fall back to "up" if nothing was hit.