feat: 马丽 sees a mouth articulating character sounds

[toshify]

On the home screen, 马丽 taps a lesson button. She then sees a multiple-choice exercise with a cartoon mouth articulating the sounds of the character under test as the audio plays.

Requires

• svg illustrations of 10ish lip states
• data-structure to hold articulation states (s-a-n, yi, w-u) with duration of each state
• an animation framework for transitioning between states in sync with audio file