Aulvar/Dock — reverse-engineered prompt

Build me a polished Dock style UI component in TypeScript and TSX that I can drop into a web app. I want it to feel like a modern app launcher bar, fixed near the bottom, with a row of icons or actions, smooth hover effects, clear active and pressed states, and nice motion that feels premium without being distracting. It should be easy to customize the items, labels, links, selected item, colors, and spacing.

Please make it responsive, keyboard friendly, and decent on touch screens too. Add support for light and dark backgrounds, sensible defaults, and a simple demo so I can open it and immediately see how it works. Keep the code clean and reusable, and include just enough comments so I know where to change things later. If anything is unclear, use good product judgment and look up current docs online if you need to.