fix(res.send): preserve DataView byte ranges - #7511

Fixes #7510.

res.send(DataView) currently returns an empty body because Buffer.from(dataView) discards its contents. Convert only DataViews from their backing buffer, byte offset, and byte length. node:util.types.isDataView also recognizes cross-realm views.

This revisits #7433, which its author closed without merging. The fix preserves the existing Buffer, Uint8Array, and non-byte typed-array paths, including the Uint16Array compatibility concern discussed in that review. Bare ArrayBuffer support (#7362) is outside this change.

Verification on Node 24.14.1 / Linux:

• Added 11 regression cases: full, sliced, empty, and cross-realm views with ETags enabled/disabled; explicit Content-Type; HEAD; existing Uint16Array conversion.
• Eight new cases fail on the original implementation and pass with the fix.
• npm run test-ci: 1,272 passing.
• npm run lint: passed.
• No dependencies, manifests, or lockfiles changed.

AI assistance was used for investigation, implementation, and local validation.