Function dampedSpringVector3

dampedSpringVector3(
    current: Vector3,
    target: Vector3,
    velocity: Vector3,
    stiffness: number,
    damping: number,
    deltaTime: number,
    out?: Vector3,
): Vector3
Damped spring interpolation for Vector3 values.

Smoothly interpolates a 3D vector toward a target using spring physics. Perfect for position smoothing, camera follow, or object tracking.
Parameters
- current: Vector3
  Current position
- target: Vector3
  Target position to reach
- velocity: Vector3
  Velocity vector (modified in place)
- stiffness: number
  Spring stiffness (higher = faster)
- damping: number
  Damping factor (higher = less oscillation)
- deltaTime: number
  Time step in seconds
- Optionalout: Vector3
  Optional output vector to avoid allocation
Returns Vector3
New interpolated position
Example
```
// Smooth camera follow
const velocity = new THREE.Vector3();
let cameraPos = new THREE.Vector3(0, 5, 10);
const targetPos = player.position.clone();

// In update loop
cameraPos = dampedSpringVector3(
  cameraPos,
  targetPos,
  velocity,
  8,   // stiffness
  4,   // damping
  deltaTime
);
camera.position.copy(cameraPos);
```
- Defined in src/core/kinematics.ts:1822