Introduce a first-person weapon viewmodel for the pistol that peeks up
from behind the HUD, completing the classic FPS look. The viewmodel
features a subtle, smoothed bob and sway animation that responds to
player movement (forward/strafe), ramping in and out to avoid
snapping.
- Add `paintWeaponPistol` to `WolfensteinArt` as a small procedural
placeholder (360x260) for when real art is absent.
- Update `WolfensteinView` to handle both real and procedural weapon art
with appropriate origins and base positions.
- Implement `_drawWeapon` with bob/sway logic and smooth strength
transitions.
- Register the new sprite key in `wolfenstein-artwork.json`.
- Document the new `wolfenstein-weapon-pistol` asset in `sprites.md`,
including its size, depth, and behavior.
