[sanjay7178]

Summary

Reduce intermediate payload copies in bounded MPSC sends and receives while preserving delivery order, backpressure, exact capacity, and reservation behavior.

Add matched inline and boxed payload benchmarks, ready-path controls, and large-payload ownership tests covering cancellation, disconnection, and resumed sends.

Paired inline benchmark medians improved by 6–14% on Linux x86-64, with overlapping timing ranges. The larger throughput gap to Tokio remains.

closes: #401

Validation

• cargo x test
• cargo x check
• cargo x lint
• cargo x bench -- --test
• Repeated fixed-workload benchmarks with ordinary, inline, and boxed payloads, including capacity-one and capacity-1024 controls.