v0.6.3

• Makes scheduler failure a structured, replayable runner outcome. Main-context
  waits now preserve deterministic deadlocks and internal scheduler errors
  instead of panicking; deadlock traces include a compact, task-sorted wait
  state before the scheduler census.

• Routes disk-latency and pathname/file-lock suspension through cancelable
  scheduler waits. Cancellation now reaches blocked file operations through
  the std.Io bridge as error.Canceled, while partial cancellation and wait
  traces remain available to the failure report.

• Adds an opt-in out-of-process watchdog on supported POSIX hosts. A worker
  that stops reaching scheduler or trace boundaries is classified as
  non_yielding; continuing activity that exhausts the total-time or partial-
  trace bound is classified as livelock. Shared-memory observation preserves
  completed trace bytes, and ordinary passing or failing runs retain exact
  replay comparison and failure identity across the worker boundary. Real-time
  watchdog cutoffs must reproduce the same identity with nested deterministic
  trace prefixes, so timing may change prefix length but cannot hide a
  divergence within the completed history.

• Lets expectSimFailure require any combination of failure kind, error name,
  and check name through FailureExpectation. An unrelated replayable setup,
  scenario, scheduler, or invariant failure can no longer satisfy a planted-
  bug test accidentally.