add kick system

scripts/KickSystem.gd

@@ -0,0 +1,41 @@
+class_name KickSystem
+
+# Deduplication: each (A,B) pair resolved once per physics frame
+static var _frame: int = -1
+static var _pairs: Dictionary = {}
+
+# Called by a flying kickable when it detects another kickable.
+# Returns true if a merge happened (both objects will despawn).
+static func resolve(owner: Node3D, other: Node3D, owner_vel: Vector3) -> bool:
+	var f := Engine.get_physics_frames()
+	if f != _frame:
+		_frame = f
+		_pairs.clear()
+
+	var id_lo := mini(owner.get_instance_id(), other.get_instance_id())
+	var id_hi := maxi(owner.get_instance_id(), other.get_instance_id())
+	var key   := str(id_lo) + "_" + str(id_hi)
+	if _pairs.has(key):
+		return false
+	_pairs[key] = true
+
+	var other_vel: Vector3 = other.get("fly_vel") if other.get("fly_vel") != null else Vector3.ZERO
+	var speed_a := Vector2(owner_vel.x, owner_vel.z).length()
+	var speed_b := Vector2(other_vel.x, other_vel.z).length()
+	var collision_speed := speed_a + speed_b
+
+	# ── 1. Merge ──────────────────────────────────────────────────────────────
+	if owner.has_method("can_merge_with") and owner.call("can_merge_with", other, collision_speed):
+		owner.call("do_merge_with", other)
+		return true
+
+	# ── 2. Damage ─────────────────────────────────────────────────────────────
+	var mod_a: float = owner.get("damage_modifier") if owner.get("damage_modifier") != null else 0.0
+	var mod_b: float = other.get("damage_modifier") if other.get("damage_modifier") != null else 0.0
+
+	if is_instance_valid(other) and other.has_method("apply_collision_damage") and mod_a > 0.0:
+		other.call("apply_collision_damage", collision_speed * mod_a)
+	if is_instance_valid(owner) and owner.has_method("apply_collision_damage") and mod_b > 0.0:
+		owner.call("apply_collision_damage", collision_speed * mod_b)
+
+	return false