feat: Introduce a settings manager and UI for configuring video, audio, and control keybinds.

scripts/ui/settings_menu.gd

@@ -162,6 +162,30 @@ func _input(event):
 	if listening_action != "" and event is InputEventKey and event.pressed:
 		# Capture the key
 		var keycode = event.keycode
+		
+		# PREVENT DUPLICATES (User Request)
+		var existing_action = SettingsManager.is_key_used(keycode)
+		if existing_action != "" and existing_action != listening_action:
+			# Visual Feedback for Error
+			var error_btn = get_node_or_null("%" + listening_action.to_pascal_case() + "Btn")
+			if error_btn:
+				error_btn.text = "ALREADY USED!"
+				error_btn.modulate = Color(1.0, 0.3, 0.3) # Red error
+				
+				# Play sound if available
+				var sfx = get_node_or_null("/root/SfxManager")
+				if sfx and sfx.has_method("play_rpc"):
+					sfx.rpc("play_rpc", "error") # Assumes an error sound exists
+				
+				# Reset listening but keep text for briefly before reverting
+				listening_action = ""
+				await get_tree().create_timer(1.2).timeout
+				_update_all_key_labels()
+			
+			get_viewport().set_input_as_handled()
+			return
+			
+		# Proceed with remapping if not a duplicate
 		SettingsManager.set_control(listening_action, keycode)
 		
 		# Feedback and Reset