Track PR #2521: reduce httpx response memory footprint

[coderabbitai]

Summary

Track the work proposed in PR #2521 to reduce httpx memory usage by:

• removing redundant response body copies
• lowering the default response read size to 50 MB
• preserving raw and decoded response-body behavior
• adding regression coverage for response-memory behavior and body metrics

Rationale

PR #2521 aims to reduce peak memory consumption in response handling without regressing decoding behavior, raw body access, or body-derived metrics.

Affected areas

• common/httpx/httpx.go
• common/httpx/option.go
• common/httpx/response_memory_test.go
• README.md

Acceptance criteria

• The default response read size is updated to 50 MB and documentation reflects the new default.
• Redundant response body copies are removed from the response handling path.
• Raw response bytes remain available where required, including when decoded data differs from raw bytes.
• Existing or added tests cover raw body handling, decoded body handling, and word/line metric behavior.
• The change is tracked against PR reduce memory #2521 for review and follow-up.

Backlinks

• Pull request: reduce memory #2521
• Requesting comment: reduce memory #2521 (comment)