Function normalize_mobile_attributes 

pub fn normalize_mobile_attributes(attributes: &mut Annotated<Attributes>)

Normalizes mobile-specific attributes on a span.

• Sets sentry.mobile: "true" if the SDK is a known mobile SDK.
• Sets sentry.main_thread: "true" if the SDK is mobile and thread.name is "main".
• Removes mobile measurement attributes that exceed 180 seconds.
• Normalizes V1 app_start_cold/app_start_warm into unified app.vitals.start.* attributes.
• Derives device.class from device attributes if not already set.