fix(http): support binary request bodies

[iamanaws]

Description

Fix patched fetch support for binary request bodies.

This updates the native HTTP bridge path so fetch() requests with Blob/binary bodies preserve the original bytes instead of serializing the body as {}.

Change Type

• Fix
• Feature
• Refactor
• Breaking Change
• Documentation

Rationale / Problems Fixed

Related issue: #6177

Specific repro comment: #6177 (comment)

I updated the original HTTP/fetch repro to the latest Capacitor version here:

https://github.com/iamanaws/capacitor-http-tester

The original HTTP/fetch cases from the issue now pass for me on web, Android, and iOS, but one binary request-body issue remained: a plain fetch() POST with a Blob body works on web, but native Capacitor patched fetch did not preserve the Blob bytes correctly.

Observed Android result before this fix:

{
  "contentType": "application/octet-stream",
  "length": 2,
  "text": "{}"
}

This looks similar to #6126, but for sending a Blob instead of receiving one.

This also breaks floccus (floccusaddon/floccus#1608) because isomorphic-git/http/web uses fetch, and Git smart HTTP needs binary request bodies.

Tests or Reproductions

Failing repro on current Capacitor version:
https://github.com/iamanaws/capacitor-http-tester

Proof branch using this Capacitor patch (from local source):
https://github.com/iamanaws/capacitor-http-tester/tree/repro/binary-request-body-support

Tested with the repro app on Android, iOS, and Web
With this patch, the Blob request-body test passes on Android and iOS.

Screenshots / Media

N/A

Platforms Affected

• Android
• iOS
• Web

Notes / Comments

Web already preserves the Blob body correctly. This PR fixes native patched fetch request body handling.

[marcelklehr]

@iamanaws Woop woop, thank you so much for this contribution!