feat: 增加NPC范鲸晶

- player场景增加RayCast2D
- 增加npc场景
- 增加NPC对话气泡

scenes/characters/NPCController.gd

@@ -0,0 +1,29 @@
+extends CharacterBody2D
+
+signal interaction_happened(text)
+
+@export var npc_name: String = "NPC"
+@export var dialogue: String = "欢迎来到WhaleTown，我是镇长范鲸鱼"
+
+func _ready():
+	$Sprite2D.texture = preload("res://assets/characters/npc_286_241.png")
+	$Sprite2D.hframes = 4
+	$Sprite2D.vframes = 4
+	
+	# Start Idle Animation
+	if has_node("AnimationPlayer"):
+		$AnimationPlayer.play("idle")
+	
+	# Ensure interaction layer
+	collision_layer = 3 # Layer 1 & 2 (Blocking)
+	collision_mask = 3
+
+func interact():
+	show_bubble(dialogue)
+	interaction_happened.emit(dialogue)
+	return null
+
+func show_bubble(text):
+	var bubble = preload("res://scenes/ui/ChatBubble.tscn").instantiate()
+	add_child(bubble)
+	bubble.set_text(text)