release(v4.2.0): pull-mode streams for browser @shade/files

4.1.0's HTTP RPC for browsers capped at inline payloads (≤ 256 KiB).
4.2.0 unlocks streams: server queues outbound chunks + control
envelopes per peer, browser long-polls the queue. Browser-to-server
writes ride the existing /v1/transfer/<id>/chunk POST routes
unchanged.

For Dispatch this unlocks mod-jar uploads (50 MB) and world-backup
downloads (100+ MB) — the actual reason browser-side @shade/files
matters.

### New API

@shade/sdk:
- shade.transferQueueRoute(opts?) — Hono app with /queue +
  /v1/transfer/* routes. Auto-configures the queue transport.
- shade.configureTransfers extended: transport + envelopeTransport
  override slots; resolveBaseUrl optional when both supplied.

@shade/transfer:
- OutboundQueue — per-peer monotonic event log with long-poll
  semantics, idle-eviction GC, ring-buffered to maxEventsPerPeer.
- QueueTransferTransport — enqueues instead of POSTing.

@shade/files:
- httpClient({ outboundQueueUrl, transferBaseUrl }) — when set,
  starts a long-poll drainer + builds a streams-bridge. fs.read /
  fs.write of >256 KiB work end-to-end.
- startQueueDrainer(shade, opts) — exported helper for advanced
  consumers driving their own drainer.

### Implementation notes

- ClientStreamsBridge's TransformStream had HWM=0 by default which
  stalled the drainer's await chain at chunk 4 (writer.write pended
  before the consumer's reader was attached). Bumped to HWM=64 so
  the receive loop can buffer ahead of the consumer.

### Tests

3 new integration tests in tests/integration/http-rpc-streams.test.ts:
4 MiB streamed read round-trip, inline-only error path, idle-timeout
long-poll behaviour.

Wire-compatible. Source-compatible. Lockstep bump to 4.2.0.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/shade-files/src/client/streams-bridge.ts

@@ -102,7 +102,16 @@ export async function createClientStreamsBridge(
     const readStreamId = incoming.metadata.userMetadata?.[META_KEY_READ_STREAM_ID];
     if (readStreamId === undefined) return;
 
-    const ts = new TransformStream<Uint8Array, Uint8Array>();
+    // Generous HWM so the receiver-side write loop (drainer →
+    // engine.receiveChunk → sink.write) doesn't stall on backpressure
+    // before the consumer's reader is wired up. The reader still
+    // applies its own backpressure once it's consuming, but we no
+    // longer race fs.read's await on stream-init against the consumer
+    // attaching its reader.
+    const ts = new TransformStream<Uint8Array, Uint8Array>(undefined, undefined, {
+      highWaterMark: 64,
+      size: (chunk?: Uint8Array) => (chunk === undefined ? 0 : 1),
+    });
     let handle: TransferHandle;
     try {
       handle = await incoming.accept({