feat: add double-barrel shotgun weapon, player movement state machine, and procedural sound assets

movement/states/state_slide.gd

@@ -14,6 +14,9 @@ func enter(_data: Dictionary = {}) -> void:
 	elapsed = 0.0
 	machine.register_chain_mechanic("slide")
 
+	if machine.player.slide_player and not machine.player.slide_player.playing:
+		machine.player.slide_player.play()
+
 	# Save original capsule height and halve it
 	var shape: CapsuleShape3D = _get_capsule()
 	if shape:
@@ -38,6 +41,10 @@ func enter(_data: Dictionary = {}) -> void:
 
 func exit() -> void:
 	machine.slide_cooldown_timer = params.slide_cooldown
+	
+	if machine.player.slide_player:
+		machine.player.slide_player.stop()
+
 	# Restore original capsule height
 	var shape: CapsuleShape3D = _get_capsule()
 	if shape and _saved_capsule_height > 0.0:
@@ -47,6 +54,10 @@ func exit() -> void:
 func update(delta: float) -> void:
 	elapsed += delta
 	var player := machine.player
+	
+	if player.slide_player and not player.slide_player.playing:
+		player.slide_player.play()
+		
 	var vel: Vector3 = player.velocity
 
 	# ── Apply friction to horizontal velocity ─────────────────────────────