Backend client_state read/write broken in 0.6.8

[masenf]

Describe the bug
The client_state is no longer a simple value in 0.6.8, so accessing it from the backend returns an internal dictionary of values.

To Reproduce

import reflex as rx

cs = rx._x.client_state("cs", 0)


class State(rx.State):
    def be_increment(self):
        return cs.retrieve(callback=State.do_increment)

    def do_increment(self, old_value):
        print(f"{old_value=}")
        return cs.push(old_value + 1)


def counter() -> rx.Component:
    return rx.hstack(
        cs,  # needed for 0.6.7 compatibility
        rx.button(f"Client Increment: {cs.value}", on_click=cs.set_value(cs.value + 1)),
        rx.button(f"Server Increment: {cs.value}", on_click=State.be_increment),
    )

Expected behavior
Same behavior as 0.6.7: both client and server increment against the client_state var should work

Specifics (please complete the following information):

• Python Version: 3.12.8
• Reflex Version: 0.6.8

[linear]

ENG-4402 Backend client_state read/write broken in 0.6.8