Function calculateHeadBob

calculateHeadBob(
    time: number,
    speed: number,
    bobFrequency?: number,
    bobAmplitude?: number,
): Vector3
Calculate procedural head bob offset for first-person cameras.

Generates vertical and horizontal oscillation based on walking speed. Creates a sense of footsteps and physical presence.
Parameters
- time: number
  Accumulated time (grows each frame)
- speed: number
  Current movement speed (units/sec)
- bobFrequency: number = 10
  Oscillation frequency in Hz. Default: 10
- bobAmplitude: number = 0.05
  Maximum displacement. Default: 0.05
Returns Vector3
Head bob offset vector
Example
```
let bobTime = 0;
const movementSpeed = 5.0;
const isMoving = true;

if (isMoving) {
  bobTime += deltaTime * movementSpeed;
  const bob = calculateHeadBob(bobTime, movementSpeed, 12, 0.04);
  camera.position.add(bob);
}
```
- Defined in src/core/camera.ts:576