feat(boss): 新增 EnemyBulletManager 敌方子弹子系统（SoA 池 + vs 玩家碰撞）

scripts/autoloads/enemy_bullet_manager.gd

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+## EnemyBulletManager — 敌方子弹管理器 Autoload（伤害玩家）
+## 平行于 BulletManager（玩家子弹 vs 敌人）；本池每帧检测 vs 玩家。
+## SoA 布局（ENEMY_BULLET_STRIDE=7）：[ x, y, vx, vy, lifetime, radius, damage ]
+##   0  1   2   3      4        5       6
+extends Node
+
+const ENEMY_BULLET_STRIDE: int = 7      # 禁裸整数
+const MAX_ENEMY_BULLETS:   int = 1024
+const PLAYER_HIT_RADIUS:   float = 12.0 # 玩家碰撞半径估算（与玩家标记视觉一致）
+
+var _data: PackedFloat32Array = PackedFloat32Array()
+var _active_count: int = 0
+
+func _ready() -> void:
+	_data.resize(MAX_ENEMY_BULLETS * ENEMY_BULLET_STRIDE)
+	_data.fill(0.0)
+
+func _physics_process(delta: float) -> void:
+	var player: Vector2 = PlayerManager.get_position()
+	var i: int = 0
+	while i < _active_count:
+		var base: int = i * ENEMY_BULLET_STRIDE
+		_data[base + 0] += _data[base + 2] * delta
+		_data[base + 1] += _data[base + 3] * delta
+		_data[base + 4] -= delta
+		if _data[base + 4] <= 0.0:
+			_swap_and_pop(i)
+			continue
+		var dx: float = _data[base + 0] - player.x
+		var dy: float = _data[base + 1] - player.y
+		var rr: float = _data[base + 5] + PLAYER_HIT_RADIUS
+		if dx * dx + dy * dy <= rr * rr:
+			PlayerStats.take_damage(_data[base + 6])
+			VFXManager.play("hit_spark", Vector2(_data[base + 0], _data[base + 1]))
+			_swap_and_pop(i)
+			continue
+		i += 1
+
+func _swap_and_pop(idx: int) -> void:
+	var last: int = _active_count - 1
+	if idx != last:
+		var b_i: int = idx * ENEMY_BULLET_STRIDE
+		var b_l: int = last * ENEMY_BULLET_STRIDE
+		for s in ENEMY_BULLET_STRIDE:
+			_data[b_i + s] = _data[b_l + s]
+	_active_count -= 1
+
+## 生成敌方子弹，返回 id（满容返回 -1）
+func spawn_bullet(pos: Vector2, vel: Vector2, lifetime: float, radius: float, damage: float) -> int:
+	if _active_count >= MAX_ENEMY_BULLETS:
+		return -1
+	var id: int = _active_count
+	var base: int = id * ENEMY_BULLET_STRIDE
+	_data[base + 0] = pos.x
+	_data[base + 1] = pos.y
+	_data[base + 2] = vel.x
+	_data[base + 3] = vel.y
+	_data[base + 4] = lifetime
+	_data[base + 5] = radius
+	_data[base + 6] = damage
+	_active_count += 1
+	return id
+
+func get_active_count() -> int:
+	return _active_count
+
+## 渲染：SoA 位置 → MultiMesh（与 BulletManager.sync_multimesh 同法）
+func sync_multimesh(mm: MultiMesh) -> void:
+	if mm == null:
+		return
+	var n: int = min(_active_count, mm.instance_count)
+	mm.visible_instance_count = n
+	for i in n:
+		var base: int = i * ENEMY_BULLET_STRIDE
+		var r: float = _data[base + 5]
+		mm.set_instance_transform_2d(i, Transform2D(
+			0.0, Vector2(r * 2.0, r * 2.0), 0.0,
+			Vector2(_data[base + 0], _data[base + 1])))
+
+func reset() -> void:
+	_active_count = 0
+	_data.fill(0.0)

scripts/autoloads/enemy_bullet_manager.gd.uid

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+uid://ctot52kayppgs