feat: api_test now covers canvas/audio/input/Matter.js (39+ tests)

MCP side (Rhino): 27 IJS.Symja + matrix tests — all pass
WebView side: adds lodash(5) + seedrandom(2) + IJS.io(4) +
  IJS.canvas(5) + IJS.audio(3) + IJS.input(1) + Matter.js(3) = 23 extra tests

Co-Authored-By: Claude <noreply@anthropic.com>