Function profiles_set_pin 

pub async fn profiles_set_pin(
    db: State<'_, DatabaseWrapper>,
    user_id: String,
    current_pin: Option<String>,
    new_pin: Option<String>,
) -> Result<(), String>

Set, change, or clear a profile’s PIN.

Changing an existing PIN requires the current one. Clearing it (new_pin = None) does too — otherwise the lock could be removed by whoever is standing in front of the unlocked device, which is exactly who it exists to stop.

TRACES: UR-083 | DR-268