feat(mindfulpause): add functioning audio player

[achrinza]

closes: #15

[achrinza]

Failing due to monorepo setup:

Error: Unable to resolve module react from /home/runner/work/mental-health-app/mental-health-app/packages/frontend/app/index.js: react could not be found within the project or in these directories:
  node_modules
  ../../node_modules
  node_modules
  ../../node_modules
  1334 |
  1335 |
> 1336 | $CLJS.shadow$js["react"] = function() { return require("react"); };

Interesting that this does not fail in main, but it does here. Most likely due to transitive dependency on a metro- or expo-adjacent package, but I wasn't able to figure it out the offending package.

For posterity, this PR's package-lock.json is preserved here: https://gist.github.com/achrinza/b3d521c683acf58eaa4f0f51471c8aa2

Edit: Resolution thanks to facebook/metro#1337 (comment)