feat: add rigged+animated Miku player model with auto-rig pipeline

- Add miku_rigged_animated.glb (3.27MB) with 18-bone skeleton and 6 animations
  (Idle, Walk, Run, Jump, Crouch, Death) via Blender auto-rig script
- Add tools/rig_and_animate.py: reusable Blender script for rigging any humanoid
  mesh with Mixamo-compatible bone naming
- Update SkinnedPlayerModel: scale_factor, first-person mode, animation state
  matching (Idle/Walk/Run/Jump/Crouch/Death)
- Update level_runtime.gd: use skinned model for local player, procedural
  humanoid for remote players
- Update skin_manager.gd and test_level_builder.gd to use animated model
- Fix Godot 4.2.1 'is not Type' syntax in 5 weapon files
- Add editor/import_miku_to_tscn.gd for editor-based GLB import

weapons/rocket_swarm.gd

@@ -151,7 +151,7 @@ func _fire() -> void:
 		var fire_dir = (base_dir + right * x_dir + up * y_dir).normalized()
 		_spawn_custom_projectile(proj_origin, fire_dir)
 		
-		if multiplayer.has_multiplayer_peer() and multiplayer.multiplayer_peer is not OfflineMultiplayerPeer:
+		if multiplayer.has_multiplayer_peer() and not(multiplayer.multiplayer_peer is OfflineMultiplayerPeer):
 			player.server_play_fire_effects.rpc_id(1, proj_origin, fire_dir, weapon_name, false)
 
 var _current_aim_dir: Vector3 = Vector3.ZERO