It sounds like behind-the-switch relay is your best bet here. You would need to wire the smart bulb directly to line so it’s always powered (this way you can control it independently of the Z-Wave relay) OR put it on load of the relay and this way you’ll need to turn the relay on, rather than the bulb, in ST to control the light via Z-Wave. This will allow you to cut power to the bulb if needed (for reset or safety).
One thing to remember is that having the relay behind the switch and controlling the light from the hub will make the wall switch behave like a 3-way switch and it will no longer have its position synced to the status of the light. That means you’ll sometimes need to toggle the switch down to turn the light ON and the switch may be toggled down, so in the “off” position when the light is on.
The Qubino relays will go on sale starting tomorrow so it’s a good time to tackle this project