Generally revise child safety restraint system laws

This bill updates Montana's child safety restraint laws to require children under six years old and weighing less than 60 pounds to use age-appropriate car seats, with specific rules for rear-facing seats for children under two and booster seats for those between four and eight years old. It clarifies legal definitions for terms like "booster seat" and "properly restrained," and establishes that child safety seats must be installed and used according to manufacturer instructions. The law also lists exemptions for certain vehicles like ambulances, motorcycles, and small two-person vehicles, while allowing temporary exemptions in emergency situations where a child's life is at risk.