机械手在 3D 钢琴上自动演奏《欢乐颂》，附音符时间轴

Build an interactive 3D web app showing a white robotic hand with five articulated fingers playing a piano keyboard. Use a dark, minimal interface with a title card reading like a mechanical pianist, a side panel listing each finger with its state, and a note timeline along the bottom showing targets for every finger. Load a built-in melody, Ode to Joy, and let the hand play it on its own: fingers press the correct keys in time, the wrist shifts along the keyboard, and keys depress visibly. Add play and pause, a tempo control, camera presets such as studio and overhead, and the ability to import a MIDI file. Add synthesized piano sound that matches the pressed keys. Deliver it as a self-contained project that runs in the browser. Done means the whole tune plays accurately with synchronized motion, sound and timeline cursor.