fix(capabilities): copy wasm request bodies before send

[bengl]

What

Copy WASM-backed request bodies into Node-owned memory before passing them to http.request().write().

Why

Node can queue ClientRequest writes before a socket is assigned. If the queued chunk is a Uint8Array view over WebAssembly.Memory, a later memory.grow() detaches that buffer and Node can throw asynchronously from _flushOutput, outside the transport retry path.

This matches the dd-trace-js system-test crash from PR 9139:

TypeError: Cannot perform Construct on a detached ArrayBuffer
    at new Uint8Array (<anonymous>)
    at new FastBuffer (node:internal/buffer:961:5)
    at Function._uint8ArrayToBuffer (node:stream:142:10)
    at _write (node:internal/streams/writable:312:22)
    at ClientRequest._flushOutput (node:_http_outgoing:1152:18)

Verification

• node --check crates/capabilities/src/http_transport.js
• node --check test/http_transport.js
• node --test test/http_transport.js

[github-actions]

Overall package size

Self size: 30.16 MB
Deduped: 30.16 MB
No deduping: 30.16 MB

Dependency sizes

| name | version | self size | total size | |------|---------|-----------|------------|

_{🤖 This report was automatically generated by heaviest-objects-in-the-universe}