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

movement/states/state_wall_run.gd

@@ -22,6 +22,9 @@ func enter(_data: Dictionary = {}) -> void:
 	machine.on_ground = false
 	_last_vel = machine.player.velocity
 
+	if machine.player.wallrun_player and not machine.player.wallrun_player.playing:
+		machine.player.wallrun_player.play()
+
 	var hvel := Vector3(machine.player.velocity.x, 0.0, machine.player.velocity.z)
 	_current_tangent = machine.wall_normal.cross(Vector3.UP).normalized()
 	if hvel.dot(_current_tangent) < 0.0:
@@ -43,6 +46,9 @@ func exit() -> void:
 	var rig = _get_camera_rig()
 	if rig:
 		rig.clear_wall_tilt()
+	
+	if machine.player.wallrun_player:
+		machine.player.wallrun_player.stop()
 
 
 func update(delta: float) -> void:
@@ -57,6 +63,9 @@ func update(delta: float) -> void:
 	var player := machine.player
 	var vel: Vector3 = player.velocity
 	
+	if player.wallrun_player and not player.wallrun_player.playing:
+		player.wallrun_player.play()
+	
 	if vel.distance_squared_to(_last_vel) > 100.0:
 		machine.wall_normal = Vector3.ZERO
 		machine.wall_side = 0.0