feat: add timeout duration to ReceiveTimeout message

[He-Pin]

Summary

• Convert ReceiveTimeout from a case object singleton to a final case class ReceiveTimeout(timeout: FiniteDuration) so the message carries the configured timeout duration
• Users can now access the timeout directly from the message handler: case timeout: ReceiveTimeout => log.info("timeout: {}", timeout.timeout)
• Closes ReceiveTimeout contains no information #2569

Motivation

Previously ReceiveTimeout was a case object with no information, making it impossible to log or inspect the timeout value without separately accessing context.receiveTimeout. As noted in the issue, this made logging awkward:

case ReceiveTimeout timeout -> {
    log.info("SessionEntity [{}] receive timeout :[{}], will stop itself", timeout, getSelf().path());
    getContext().stop(getSelf());
}

Changes

• actor/src/main/scala/.../Actor.scala: Convert ReceiveTimeout from case object to final case class with timeout: FiniteDuration field and Java API getTimeout method
• actor/src/main/scala/.../dungeon/ReceiveTimeout.scala: Scheduler now sends ReceiveTimeout(timeout) instead of the singleton
• All pattern matches: Updated from stable identifier patterns (case ReceiveTimeout =>) to type patterns (case _: ReceiveTimeout =>)
• Java API: Updated from matchEquals(ReceiveTimeout.getInstance(), ...) to match(ReceiveTimeout.class, ...)
• MiMa filters: Added binary compatibility exclusion for 2.0.x
• Tests: Added new test verifying the timeout duration is carried correctly

Breaking changes (2.0)

• ReceiveTimeout is no longer a singleton; pattern matches must use type patterns
• ReceiveTimeout.getInstance() removed; Java users should use .match(ReceiveTimeout.class, ...)

Test plan

• actor-tests/testOnly *.ReceiveTimeoutSpec — 15 tests pass (including new "carry the configured timeout duration" test)
• actor-typed-tests/testOnly *.CancelReceiveTimeoutSpec — passes
• All affected modules compile: actor, actor-typed, cluster, cluster-tools, cluster-sharding, distributed-data, persistence, docs