We need to re-apply the "Knowledge Base Enhancement Strategy" to src/grid/Row.mjs. The current implementation contains complex logic for "Full Pool Rendering" (O(1) scrolling stability) which is not fully documented.

Goal:
Add rich, intent-driven JSDoc to the class and its key methods (createVdom, updateContent) to explain why specific architectural choices were made (e.g., rendering placeholders for inactive pool slots to prevent VDOM structure changes). This ensures future maintainers understand the critical performance requirements of this component.