Fixed

• Resource lifecycle: BindGroup/Pipeline Release() bypasses ref-counting —
  Release() called dq.Defer(lastSubmissionIndex) directly, ignoring the
  ResourceRef ref-counting system. On shared encoder path, this caused
  use-after-free: HAL resource destroyed while GPU still processing commands.
  Now Release() calls ref.Drop() — HAL destruction deferred until ALL
  refs (user + GPU) are dropped. Matches Rust wgpu Arc<BindGroup> pattern.
  Applied to: BindGroup, RenderPipeline, ComputePipeline. (#287)

• DestroyQueue deadlock: Triage → onZero → Defer re-entry —
  Triage() held mutex while executing callbacks. When onZero fired and
  called Defer(), it tried to acquire the same mutex → deadlock. Now
  callbacks execute outside the lock. Same fix applied to FlushAll().

Tests

• 6 new lifecycle tests: refcount transitions, Release-before-Submit,
  Release-without-Clone, mixed-resource TrackedSubmission, buffer binding scenario