Make Bedrock saturation and regeneration match Java Edition

In Java Edition, saturation is used for fast health regeneration, making high-saturation foods valuable during combat. In Bedrock Edition, regeneration is slower and saturation has much less impact on immediate healing. This creates a gameplay difference between the two official editions and makes food feel less responsive during combat in Bedrock. Bringing Bedrock's saturation-based regeneration in line with Java would improve parity, consistency, and combat responsiveness without affecting controls, touch devices, or accessibility.