Add sound effects and character scripts

- Imported new sound effects: "Low Boing", "Low Whoosh", and "Pew" with corresponding import files.
- Created a new character script for "Hen" with basic AI and attack functionality.
- Implemented an effect controller script for managing particle effects with one-shot functionality.

scripts/Contents/Characters/Hen.gd

@@ -0,0 +1,15 @@
+extends EntityBase
+class_name Hen
+
+func _ready():
+	fields[FieldStore.Entity.MAX_HEALTH] = 75
+	fields[FieldStore.Entity.MOVEMENT_SPEED] = 0.25
+	super._ready()
+
+func ai():
+	move(currentFocusedBoss.position - position)
+	tryAttack(0)
+func attack(type):
+	if type == 0:
+		var weaponPos = findWeaponAnchor("normal")
+		BulletBase.generate(preload("res://components/Bullets/HenBomb.tscn"), self, weaponPos, 0)