Function updateFacingTowardOpponent

updateFacingTowardOpponent(
    facing: BodyFacing,
    playerPosition: Position,
    opponentPosition: Position,
    deltaTime: number,
    currentTime: number,
): BodyFacing
Updates facing direction to point toward opponent

Calculates target angle based on opponent position and updates body facing state with smooth rotation.
Parameters
- facing: BodyFacing
  Current body facing state
- playerPosition: Position
  Player's current position
- opponentPosition: Position
  Opponent's current position
- deltaTime: number
  Time elapsed since last update in seconds
- currentTime: number
  Current timestamp in milliseconds
Returns BodyFacing
Updated body facing state
Example
```
const updated = updateFacingTowardOpponent(
  facing,
  { x: 100, y: 200 },
  { x: 300, y: 200 },
  0.016,
  Date.now()
);
// Faces toward opponent (pointing right in this case)
```
Korean
상대방향하기업데이트
- Defined in systems/animation/systems/BodyFacingSystem.ts:339