Advanced AI Prompt for Neumorphic Depth-Shifting Cursor

Act as a Skeuomorphic UI Designer. Implement a complex custom cursor script that transforms the user's mouse into a literal 'light source' illuminating a massive Neumorphic design system. As the physical cursor travels across the viewport, the CSS `box-shadow` properties of all interactive elements on the page must mathematically invert and shift their X/Y offsets relative to the real-time [LIGHT_SOURCE_X] and [LIGHT_SOURCE_Y] coordinates, generating a severe [SHADOW_INTENSITY]. Write a highly optimized Vanilla JavaScript utility that calculates the vector angles and broadcasts them globally via CSS custom properties. Provide a detailed, technical warning in the comments explaining the extreme CPU/GPU paint performance implications of updating complex box-shadows on every `mousemove`, and mandate the exact `lodash.throttle` or `requestAnimationFrame` logic required to maintain a playable frame rate on low-end devices.