[Bedrock] Button text briefly becomes black squares when switching menus

This is a client-side UI/font rendering bug. Rapid menu switching causes a font glyph atlas/texture binding race: the glyph texture is not ready or not bound in time, so button text briefly renders as black placeholder squares. It is not network-related and can be triggered repeatedly by fast menu switching. Expected: Button text should always render normally. Actual: Button text briefly becomes black squares during fast menu switching.