♻️(frontend) reorganize starting frontend code

- we now have "features" to try to organize code by intent instead of
code type. everything at the root of frontend, not in feature/, is
global
- customized the panda config a bunch to try to begin to have an actual
design system. The idea is to prevent using arbitrary values here and
there in the code, but rather semantic tokens
- changed the userAuth code logic to handle the fact that a 401 on the
users/me call is not really an error per say, but rather an indication
the user is not logged in

src/frontend/package.json

@@ -14,7 +14,6 @@
     "@livekit/components-styles": "1.0.12",
     "@pandacss/preset-panda": "0.41.0",
     "@tanstack/react-query": "5.49.2",
-    "classnames": "2.5.1",
     "livekit-client": "2.3.1",
     "react": "18.2.0",
     "react-aria-components": "1.2.1",