http: preserve socket errors as response error causes - #66061

When a socket error interrupts an HTTP response, the request receives the original error, but the response and its downstream pipeline receive only ECONNRESET: aborted. The underlying cause is lost.

Preserve that original error as cause on the response error, keeping the existing ECONNRESET code, aborted message, and event order. This applies to TLS errors and actual TCP resets alike. Premature closure without an underlying error leaves cause absent.

This came out of investigating #66001. I could not reproduce or identify the root cause of the reported TLS decryption failure on an intact stream, but confirmed the separate loss of error context described above. The original failure remains unresolved; this PR is limited to preserving diagnostic context. The TLS regression test deliberately sends an invalid record after response headers have been received to test error propagation.

Validation on macOS arm64:

• Release build succeeded.
• All 721 selected HTTP, HTTPS, TLS, error, and TCP reset tests passed.
• Regression coverage includes TLS 1.2/1.3, real TCP resets, explicit destruction, closure without an error, cause identity and property attributes, and event order.
• The TLS regression test fails on unmodified Node v24.21.0 because cause is missing.
• JavaScript lint, Markdown lint, and git diff --check passed.

Refs: #66001

AI assistance: GPT-6 assisted with investigation, implementation, tests, and this description. The compatibility approach was selected through discussion with the contributor; the validation above was run by the assistant.