v0.2.0

• Context::onTerminate() returns an unsubscribe closure
  (\Closure(): void) instead of void; calling it removes the listener,
  and it is a no-op once the listener ran. Source-compatible: callers that
  ignore the return value are unaffected (#1).
• A terminated context state detaches from its parent and releases its
  listeners and children, so a long-lived parent no longer accumulates every
  cancelled or expired child it derived. withValue() now shares its
  parent's state instead of attaching a new child per call (#1).
• withTimeout() no longer overflows: a timeout beyond the representable
  range saturates at a PHP_INT_MAX deadline, and a zero or negative timeout
  yields an immediate deadline (the context is expired on first
  observation) (#2).
• ContextExpiredException accepts an optional $previous throwable, so a
  transport adapter can keep the underlying timeout as the cause.
• Documented propagating a budget across a process boundary: send
  remainingMs(), rebuild with withTimeout($ms / 1000) on the receiving
  side (#4).
• README/llms.txt placeholders replaced with the real API reference, Russian
  README added, property tests for subtree cancellation and nearest-ancestor
  value lookup, regression-corpus caching in CI (#3).