Restore Omit on public plugin-sdk ReplyPayload; set trustedLocalMedia via
runtime assertion in speech-core and explicitly on dispatch TTS-only finals.
Co-authored-by: Cursor <cursoragent@cursor.com>
Avoid per-block final-mode synthesis (duplicate with dispatch tail). Mark
TTS output as trusted local media and pass the flag through the TTS-only
final payload WebChat consumes after block streaming.
Fixes#82628
Co-authored-by: Cursor <cursoragent@cursor.com>