docs: say what the connection reads from the voice credential

It reads the token, model, transcription model and tier for diagnostics and
cost accounting, so the credential is not opaque to it. Also lists requestToken's
authMode option in APPLICATION.md.

docs/APPLICATION.md

@@ -158,7 +158,7 @@ routing and regional caches. Request parameters cannot override these endpoints.
 Voice controls accept an action runner and a controller factory through
 `createVoiceCommands` (`./voice/commands`). The default Realtime controller owns
 microphone tracks, playback, push-to-talk, tool cancellation and radio handoff.
-Its backend supplies `requestToken({ tier, signal })` and
+Its backend supplies `requestToken({ tier, authMode, signal })` and
 `negotiate({ offerSdp, credential, signal })`. The Realtime-compatible adapter
 (`./voice/realtime-backend`) accepts separate token and connection transports
 and endpoints. Only the short-lived client secret reaches the SDP endpoint.

docs/VOICE-OWNERSHIP.md

@@ -26,8 +26,8 @@ The backend is replaceable per deployment: `realtimeController.js` accepts it as
 `backend` option and falls back to `createRealtimeBackend()`. Its two method
 signatures live with [application construction](APPLICATION.md); what belongs here
 is the ownership. The connection is the backend's only consumer in the application.
-The resolved credential is opaque to the connection and is handed to `negotiate`
-whole. Client-secret expiry is refused inside the backend, not by the connection.
+The connection reads credential metadata for diagnostics and cost accounting,
+then passes the complete credential unchanged to `negotiate`. Client-secret expiry is refused inside the backend, not by the connection.
 `realtimeOwners.test.mjs` drives whole sessions through a substitute that
 implements only those two methods.