CodeRabbit caught a real bug in the previous commit's fix. The latch mirrors
the NATIVE refcount, but it was flipped before the invoke resolved: a rejected
release left it reading "released" while the engine still held the
suppression, so every later release short-circuited and monitor mute stayed
suppressed for good — the same stuck-suppression bug the latch exists to
prevent, just one level up.
The latch now only stays flipped if the call actually landed, and rolls back
otherwise (guarded so a newer call can't be clobbered by a stale rejection). A
downlevel addon with no arbiter leaves the latch untouched instead of
recording a hold it never acquired.
Pins the whole contract with a vm-extracted unit test on the real screen.js
function: unpaired acquires hold at most one native suppression, cycles stay
balanced across 25 song loads, a rejected release retries, and both the
downlevel and sync-throw paths are clean. Fails 3/5 against the original
branch (the refcount leak) and 2/5 against the pre-rollback version.
