v0.9.1

Fixed

• DMX universe deadlock: Fixed an ABBA deadlock between the effects loop and universe
  threads caused by reversed lock ordering of the target and rates RwLocks in
  approach_target(). This could cause lighting to freeze mid-song, after which audio
  playback and lighting would no longer function until restart. The deadlock was timing-
  dependent and could occur on any song type (legacy MIDI or DSL).

• Effects loop resilience: The persistent effects loop is now wrapped in catch_unwind
  so that a panic in a single tick cannot kill the loop thread. Panics are logged and the
  loop continues on the next tick.

• Effects loop heartbeat monitoring: Barrier threads now monitor the effects loop via an
  atomic heartbeat counter instead of waiting indefinitely. If the heartbeat is stale for 10
  seconds, the timeline is force-finished and the song completes gracefully rather than
  hanging forever.

• Lost condvar notifications: CancelHandle::notify() now acquires the mutex before
  signaling, preventing a race where notifications could be lost between a waiter's predicate
  check and its condvar sleep.

• Blocking mutexes in async code: The state sampler and TUI tick now acquire
  parking_lot::Mutex locks via spawn_blocking instead of blocking the tokio runtime
  directly. The TUI log buffer was also migrated from std::sync::Mutex to
  parking_lot::Mutex for consistency with the rest of the codebase.