[norbot7865]

Summary

• compile per-voice hard-release output bindings for synths with no enabled envelope
• keep idle voices muted, restore output controls on trigger, and mute again for scheduled or explicit release
• preserve normal Sointu release tails for synths that define an envelope
• document the release behavior and cover duration, explicit release, and voice reuse

Tests

• go test ./...
• go test -race ./...

Closes #24