fix: add smart entry scene (client vs server via headless detection)

scripts/entry.gd

@@ -0,0 +1,18 @@
+## Entry — Smart entry point.
+## Loads the server scene if running headless (dedicated server),
+## or the client scene if running with a display (Windows client).
+extends Node
+
+func _ready() -> void:
+	var is_headless := DisplayServer.get_name() == "headless"
+	
+	if is_headless:
+		# Dedicated server mode
+		var server_scene = preload("res://scenes/server/server_main.tscn")
+		add_child(server_scene.instantiate())
+		print("[Entry] Starting in SERVER mode (headless)")
+	else:
+		# Client mode (Windows, etc.)
+		var client_scene = preload("res://scenes/client/client_main.tscn")
+		add_child(client_scene.instantiate())
+		print("[Entry] Starting in CLIENT mode (display available)")