Fixed pistol and knife sprites for retail. Added firing mechanism.

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

lib/features/player/weapons/knife.dart

@@ -5,14 +5,13 @@ class Knife extends Weapon {
     : super(
         name: "Knife",
         idleSprite: 416,
-        fireFrames: [417, 418, 419],
+        fireFrames: [417, 418, 419, 420],
         damage: 15,
         msPerFrame: 120,
       );
 
   @override
   bool fire(int currentTime, {required int currentAmmo}) {
-    // Knife doesn't need ammo!
     if (state == WeaponState.idle) {
       state = WeaponState.firing;
       frameIndex = 0;