feat: 场景与核心玩法脚本（双机型/波次/Boss/道具/炸弹/地面单位/浮游炮激光）

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

scripts/wave_spawner.gd

@@ -0,0 +1,163 @@
+class_name WaveSpawner
+extends Node
+## 波次生成器：时间线循环刷敌，每轮提升难度。
+
+var difficulty := 1.0
+var game: Game
+
+
+func _ready() -> void:
+	call_deferred("_run")
+
+
+func _run() -> void:
+	game = get_tree().get_first_node_in_group("game") as Game
+	await get_tree().create_timer(0.8).timeout
+	var round_num := 1
+	while true:
+		difficulty = minf(1.0 + (round_num - 1) * 0.12, 1.8)
+		await _play_round()
+		await _wait_playing()
+		# 关底 Boss 战
+		if game != null and is_instance_valid(game):
+			game.show_boss_warning()
+		await _timer(2.0)
+		await _wait_playing()
+		var boss: Boss = null
+		if game != null and is_instance_valid(game):
+			boss = game.spawn_boss(difficulty)
+		while boss != null and is_instance_valid(boss):
+			await _timer(0.3)
+		await _wait_playing()
+		await _timer(2.5)
+		round_num += 1
+		await get_tree().create_timer(2.5).timeout
+
+
+func _play_round() -> void:
+	await _wait_playing()
+	await _column(140.0)
+	await _timer(3.2)
+
+	await _wait_playing()
+	_v_formation(270.0)
+	await _timer(3.8)
+
+	await _wait_playing()
+	_sine_squad(170.0)
+	_sine_squad(370.0)
+	await _timer(3.8)
+
+	await _wait_playing()
+	_fortress(120.0)
+	_fortress(420.0)
+	await _timer(2.6)
+
+	await _wait_playing()
+	await _column(400.0)
+	await _timer(0.8)
+	await _column(120.0)
+	await _timer(3.0)
+
+	await _wait_playing()
+	_medium(1, 210.0)
+	await _timer(4.0)
+
+	await _wait_playing()
+	_ship(190.0)
+	await _timer(4.0)
+
+	await _wait_playing()
+	_v_formation(160.0)
+	await _timer(1.4)
+	_v_formation(380.0)
+	await _timer(3.6)
+
+	await _wait_playing()
+	_sine_squad(270.0)
+	_fortress(270.0)
+	await _timer(3.4)
+
+	await _wait_playing()
+	_medium(-1, 260.0)
+	await _column(270.0)
+	_ship(380.0)
+	await _timer(4.2)
+
+
+## 游戏结束时挂起等待，避免继续刷敌
+func _wait_playing() -> void:
+	while game == null or game.state != Game.State.PLAYING:
+		await get_tree().create_timer(0.5).timeout
+
+
+func _timer(duration: float) -> void:
+	await get_tree().create_timer(duration).timeout
+
+
+## 纵队：同一直线依次下压，头机掉宝
+func _column(x: float) -> void:
+	for i in 5:
+		_spawn_small(x, -30.0 - 46.0, 190.0 * difficulty, 0.0, 2.0, 0.0, true, 250.0 * difficulty, i == 0)
+		await _timer(0.32)
+
+
+## V 字编队：5 机整体压境，仅领队开火并掉宝
+func _v_formation(center_x: float) -> void:
+	var offsets := [Vector2(0.0, -30.0), Vector2(-44.0, -66.0), Vector2(44.0, -66.0), Vector2(-88.0, -102.0), Vector2(88.0, -102.0)]
+	for i in offsets.size():
+		var offset: Vector2 = offsets[i]
+		var is_leader := i == 0
+		_spawn_small(center_x + offset.x, offset.y, 150.0 * difficulty, 16.0, 1.6, 0.0, is_leader, 240.0 * difficulty, is_leader)
+
+
+## 摆动机队：同路径依次进场、正弦横摆，头机掉宝
+func _sine_squad(x: float) -> void:
+	for i in 4:
+		_spawn_small(x, -30.0, 130.0 * difficulty, 72.0, 1.8, 0.0, randf() < 0.5, 230.0 * difficulty, i == 0)
+		await _timer(0.4)
+
+
+## 中型轰炸机横掠
+func _medium(p_side: int, y: float) -> void:
+	var enemy := EnemyMedium.new()
+	enemy.setup(p_side, y, 112.0 * difficulty, 235.0 * difficulty, maxf(0.9, 1.6 / difficulty))
+	_add_enemy(enemy)
+
+
+## 地面固定堡垒
+func _fortress(x: float) -> void:
+	var enemy := EnemyFortress.new()
+	enemy.setup(x, -60.0, difficulty)
+	_add_enemy(enemy)
+
+
+## 驱逐舰
+func _ship(x: float) -> void:
+	var enemy := EnemyShip.new()
+	enemy.setup(x, -140.0, difficulty)
+	_add_enemy(enemy)
+
+
+func _spawn_small(
+	x: float,
+	y: float,
+	vy: float,
+	sway_amp: float,
+	sway_freq: float,
+	phase: float,
+	shoot: bool,
+	bullet_speed: float,
+	drop := false
+) -> void:
+	var enemy := EnemySmall.new()
+	enemy.setup(x, y, vy, sway_amp, sway_freq, phase, shoot, bullet_speed)
+	enemy.drops_powerup = drop
+	_add_enemy(enemy)
+
+
+func _add_enemy(enemy: EnemyBase) -> void:
+	var container := get_tree().get_first_node_in_group("enemies")
+	if container == null:
+		return
+	container.add_child(enemy)