Expose pull-based collective lifecycle events

[dolpm]

Summary:
Adds an opt-in, pull-based collective lifecycle feed in native CollTrace and exposes copied values through matched NCCLX and nccl4py builds.

Ownership and configuration

• NCCL_COLLTRACE=lifecycle creates one LifecycleEventFeedPlugin per lifecycle-enabled ncclComm_t. Lifecycle-only mode starts CollTrace without also installing CommDump.
• NCCL_COLLTRACE=ALL and lowercase all enable algostat, lifecycle, and trace without implicitly enabling verbose; explicit verbose composes with either alias. Unknown modes return ncclInvalidArgument before partial initialization.
• A process-local registry holds weak CollTrace references. The global reader flushes live instances, drains their plugin queues, and stable-sorts copied records by timestamp without extending communicator lifetimes.

Public API and identity

• colltrace_get_comm_id(comm) returns a monotonic process-local communicator ID.
• colltrace_get_latest_coll_id(comm) returns the latest identity for that communicator. 0 means no collective has been registered; real collective IDs are one-based. Captured collectives retain their capture identity across graph replays.
• colltrace_get_unread_events() destructively drains unread enqueue, start, and end records across lifecycle-enabled communicators. Each tuple is (replay_id, comm_id, coll_id, execution_coll_id, event_type, timestamp).
• Latest-ID state belongs to the communicator plugin, not thread-local storage. Null communicators return ncclInvalidArgument; communicators without lifecycle mode return ncclInvalidUsage.

Lifecycle correctness and build boundary

• CPU start/end timestamps are stored before semaphore publication. If a ready wait event unexpectedly reports the epoch sentinel, the poller substitutes its current timestamp so start/end state remains sticky and callbacks are not emitted repeatedly.
• The Python bridge releases the GIL around native calls, maps absent replay IDs to None, and never exposes pointers into CollTrace state.
• NCCLX and nccl4py remain a matched-build boundary because the binding links the new native symbols and layouts directly.

Reviewed By: pavanbalaji

Differential Revision: D114815651

[meta-codesync]

@dolpm has exported this pull request. If you are a Meta employee, you can view the originating Diff in D114815651.

[meta-codesync]

This pull request has been merged in 2504bbe.