feat(web): consume AppView XRPC + env setup
- appview client (lib/appview.ts) calling api.atradio.fm/xrpc/fm.atradio.*,
base from VITE_APPVIEW_URL.
- Public profiles (/profile/:actor) now read favorites/stations from the
AppView; own profile still reads from the PDS. Drop unused publicReader.
- .env.production (prod API), .env.example (reference); .env.local is
gitignored for local dev (points AppView at http://127.0.0.1:8080).