Function spawn_prompt_registration_check 

pub fn spawn_prompt_registration_check(
    is_auto: bool,
    auto_turn_pending: &mut bool,
    in_flight_live: bool,
) -> bool

Pure decision logic for the spawn_prompt registration re-check (Bug 1 fix).

Models the guard that runs inside the registration lock just before in_flight is written. Returns true if it is safe to proceed with registration (caller should write in_flight and clear auto_turn_pending); returns false if the reservation was revoked by an intervening Abort and the caller must abort the spawned task (drop start_tx).

Rules (identical to the re-check in spawn_prompt):

• Non-auto prompts (!is_auto) always return true — they are validated by handle_prompt’s is_busy() check before reaching here.
• Auto prompts: true iff auto_turn_pending && !in_flight_live.
• If returning false, the helper also defensively clears auto_turn_pending.

Used by spawn_prompt and by integration tests (not the replica scheduler).