Release v1.0.0

Changes

Added

• Initial release of slick::stream_buffer_multiplexer, a lock-free MPMC byte
  stream multiplexer built by composing slick::stream_buffer (per-producer
  SPMC byte ring) with slick::queue<record> (shared MPMC fan-in queue).
• Per-producer producer_buffer with the familiar
  prepare/commit/consume/discard/data/size interface, plus a
  .stream_buffer() accessor returning a literal slick::stream_buffer& for
  drop-in slick::dynamic_buffer interop, and a .stream_buffer_ptr()
  accessor returning std::shared_ptr<slick::stream_buffer> for shared
  ownership with slick-net's websocket_session.
• get_producer_buffer(producer_id) returning std::shared_ptr<producer_buffer>
  (or nullptr if unregistered), for shared ownership of a producer (including
  consume()) that can outlive the stream_buffer_multiplexer.
• add_producer registration API (local memory, shared-memory creator, and
  shared-memory opener overloads) with explicit producer_id, allowing any mix
  of local-memory and shared-memory producers under one shared queue. Returns
  std::shared_ptr<producer_buffer>, so the registered producer (including
  consume()) can outlive the stream_buffer_multiplexer.
• read(cursor) and read(std::atomic<uint64_t>& cursor) (work-stealing)
  returning a zero-copy multiplex_record{data, length, producer_id}.
• Three independent loss counters: shared-queue wrap loss, multiplexer-level
  loss (shared-queue entries whose producer_id is registered on this instance
  but were lapped by that producer's own ring before being dereferenced), and
  each producer's own ring loss. The multiplexer-level counter is configurable
  via SLICK_STREAM_BUFFER_MULTIPLEXER_ENABLE_LOSS_DETECTION (default: enabled
  in debug builds, disabled in release), matching slick::stream_buffer and
  slick::queue.
• Shared memory (IPC) support with producer_id <-> shm-name mapping by caller
  convention; unregistered producer ids on a consumer instance are silently
  skipped rather than treated as an error or counted as loss.

Changed

• Replaced the confusing producer_slot_count() API with
  producer_count(), which now returns the actual number of registered
  producers.
• Optimized producer lookup with a dense fast path for low producer_id
  values while still supporting sparse registrations through a fallback map.
• Clarified in the README that contiguous producer_id values, ideally
  starting at 0, provide the best lookup performance.