Fix Post-Cutscene TTS Block Reset

[JoeyBelvar]

Intent: prevent a skipped/consumed cutscene audio block from suppressing later NPC TTS after the voiced scene has moved on.

Changes:

• Adds ClearConsumedAudioGenerationBlock(...) to centralize clearing _blockAudioGeneration.
• Also clears the block when generated NPC audio is ready but playback is suppressed because a cutscene SCD arrived while the relay request was still in flight.
• Keeps logging at the existing [NPC TTS] boundary level so validation can watch for the clear event without adding per-frame noise.