perf(http1): write during header sorting

[0x676e67]

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[Copilot]

Pull Request Overview

This PR optimizes HTTP/1 header writing by eliminating intermediate header sorting and memory allocations. Instead of first sorting headers into a new HeaderMap and then iterating through them, the new approach directly writes headers during the sorting iteration process.

• Introduces a new sort_headers_for_each method that combines sorting and iteration into a single operation
• Replaces the write_headers_original_case function to use the new approach, removing the need for intermediate header storage
• Refactors control flow in client response parsing for better readability

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/header.rs	Adds sort_headers_for_each method and moves test helper function from public to test module
src/core/client/proto/h2/client.rs	Updates variable naming for clarity (orig → orig_headers)
src/core/client/proto/h1/role.rs	Refactors header writing to use new streaming approach and improves control flow structure

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