Function startup_target 

pub fn startup_target(profiles: &[Profile], ask_on_start: bool) -> StartupTarget

Decide the startup target from the profiles present and the user’s setting.

Pure, because the rule is worth testing and the inputs are trivial to state:

• No profiles at all → picker (which renders as the first-run login).
• The last-used profile has a PIN → picker, regardless of the setting. A code that could be skipped by relaunching is not a code.
• More than one profile and “ask who’s watching” is on → picker.
• Otherwise → resume, exactly as the app behaved before profiles existed.

TRACES: UR-082 | DR-274