fix(front): clean startup console noise

[MichaelUray]

Removes three sources of console noise that appear on every front-end startup
with a default or partial configuration:

1. packages/presentation/src/sound.ts — the AudioContext was created
   at module load, triggering the browser autoplay-policy warning ("The
   AudioContext was not allowed to start") on every page load. It is now
   created lazily on first use and resumed when suspended, so sound playback
   behaves exactly as before after the first user gesture.
2. plugins/love-resources/src/utils.ts — checkRecordAvailable() called
   res.json() on whatever the endpoint returned; with the recording endpoint
   absent or fronted by a proxy error page this logged a JSON parse error.
   Non-OK or non-JSON responses now simply mark recording as unavailable.
3. plugins/notification-resources/src/utils.ts — push subscription only
   checked that PushPublicKey is defined; a malformed or placeholder VAPID
   key produced an InvalidAccessError in the console. The key is now
   validated (base64url, 65-byte uncompressed P-256 point with 0x04 prefix)
   and converted to a Uint8Array before subscribing; invalid keys disable
   push cleanly instead of throwing.

No behavioural change for correctly configured deployments.

[huly-github-staging]

Connected to Huly®: UBERF-16640