[codex] fix binary request bodies

[maxvaljan]

Summary

• change NitroRequest.bodyBytes to ArrayBuffer and regenerate Nitrogen bindings
• pass normalized ArrayBuffer/typed-array request bodies through to native instead of dropping them
• write binary upload bytes into URLSession/Cronet request bodies
• add a JS regression test for ArrayBuffer and typed-array request bodies

Root Cause

The public fetch API and docs support ArrayBuffer and typed-array request bodies, but buildNitroRequest and buildNitroRequestPure set bodyBytes to undefined. The native request paths also could not upload binary bodies: iOS ignored req.bodyBytes, and Android sent a one-byte placeholder.

Notes

Cold-start prefetch entries are JSON-backed, so this PR does not try to persist raw binary prefetch bodies through bodyBytes. String and form-data prefetch behavior remains unchanged.

Validation

• bun --cwd packages/react-native-nitro-fetch test -- src/__tests__/fetch.test.ts src/__tests__/Response.test.ts
• bun --cwd packages/react-native-nitro-fetch typecheck
• bun --cwd packages/react-native-nitro-fetch nitrogen
• commit hook: staged lint + types + commitlint passed

Package-wide bun --cwd packages/react-native-nitro-fetch lint still reports existing tracked .js formatting/no-undef issues outside this diff.

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