Streams get a safety pass, compose goes stable

Stream pipeTo now respects accepted backpressure (8c6e39e)

pipeTo() no longer retries chunks that a sync writer already accepted while signaling backpressure. This fixes a bug where block-mode PushWriter could cause duplicate async writes instead of waiting for drain, improving correctness under pressure.

BroadcastWriter now rejects non-array writev input (a6696e2)

BroadcastWriter.writev() and writevSync() now validate that chunks is actually an array and throw ERR_INVALID_ARG_TYPE otherwise. That tightens the API and matches the validation covered by new tests.

stream.compose is now stable (19dd555)

The docs now mark stream.compose as Stability 2 instead of experimental. This signals the API is ready for general use.

Other misc changes

• WebStreams internal validation cleanup for highWaterMark/size coercion (13c2374)
• Debugger test flake fixes around restart/initial-break handling (9de9b9f, 3163d8a)