fix: replace Buffer.from with Uint8Array in toFormData - #11018

Fixes #10990

The only use of Buffer in client-facing code is a single Buffer.from(value) fallback in toFormData.js. Bundlers like Webpack (used by Next.js) detect this reference and pull in the full buffer polyfill into browser bundles.

Replaced with new Uint8Array(value) which is a native browser API accepted by both FormData and Node.js form-data. Also updated the error message on the Blob guard to reference ArrayBuffer/TypedArray instead of Buffer.

All 596 unit tests pass.

Summary by cubic

Replaced direct Buffer.from in toFormData with a Node-only wrapper and browser-safe Uint8Array/Blob handling to avoid bundler buffer polyfills while keeping Node behavior intact.

Description

• Summary of changes
  • Added lib/platform/node/classes/Buffer.js with isBufferAvailable() and from().
  • Updated toFormData to use the wrapper; browsers use Blob/Uint8Array.
  • Mapped ./lib/platform/node/classes/Buffer.js to ./lib/helpers/null.js for browser and React Native in package.json.
  • Updated PRE_RELEASE_CHANGELOG.md with a FormData note (refs fix: replace Buffer.from with Uint8Array in toFormData #11018, closes Remove direct usage of Buffer #10990).
• Reasoning
  • Prevents bundlers from injecting buffer polyfills in web builds while preserving Node conversion for non-spec FormData.
• Additional context
  • Main logic change is in lib/helpers/toFormData.js.

Docs

• Update /docs/ to note toFormData accepts ArrayBuffer/TypedArray in all environments; browsers produce Blob, and Node may use Buffer for non-spec FormData. No Buffer requirement in browsers.

Testing

• Added browser test: TypedArray converts to Blob and round-trips bytes.
• Added Node unit test: TypedArray converts to Buffer for non-spec FormData.
• Existing error-path test for missing Buffer still applies. No additional tests needed.

Semantic version impact

• Patch: internal implementation change only; no API changes.

^{Written for commit 832c9f8. Summary will update on new commits.}