Function port_field

fn port_field(ui: &mut Ui, state: &mut SettingsUi, s: &mut Settings) -> bool

MCP port DragValue. The app restarts the server whenever settings.mcp_port changes, so the value is held in state.port_edit while the user drags or types and only written when the gesture ends — otherwise a drag from 7337 to 7400 walks through ~60 ports and one busy port in between turns the server off. Returns true when the setting changed.