release: add v1.0 acceptance gates

[zuudevs]

Summary

Starts the v1.0 release-hardening milestone without adding feature scope. This PR turns the frozen requirements into explicit release gates and strengthens the installed/public surface checks.

New v1 Release Gate workflow

Adds two Linux release-gate jobs:

• ASan + UBSan (Clang, C++17)

  • Debug build
  • warnings as errors
  • AddressSanitizer + UndefinedBehaviorSanitizer
  • leak detection enabled
  • unit and loopback integration tests under sanitizers
  • install-consumer script excluded from the sanitizer run because its independent link step would need matching sanitizer flags

• C++20 Compatibility + Installed Consumer

  • full C++20 Release build and tests
  • warnings as errors
  • installs to a staging prefix
  • separately configures/builds/runs the installed consumer in C++20 mode

The C++20 gate has already completed successfully on an earlier hardening head, including full tests, install, separately configured installed consumer, and consumer tests.

The existing cross-platform Debug/Release CI and benchmark smoke workflows remain authoritative for Windows/Linux/macOS and benchmark coverage.

Public-header isolation gate

Every installed public header is compiled as its own translation unit using only the public include directory:

• client.hpp
• error.hpp
• headers.hpp
• request.hpp
• response.hpp
• response_limits.hpp
• result.hpp
• url.hpp

This catches missing direct includes and accidental dependencies on src/ or platform implementation headers.

Installed consumer hardening

The package consumer now includes and exercises the full public header surface rather than only the common Client/Request path.

Warning hygiene found by the gate

Clang warnings-as-errors exposed implicit signed char to unsigned-byte conversions in byte-oriented validation code. The hardening branch now makes those conversions explicit in:

• URL forbidden-byte validation
• request percent encoding and header validation
• response header/reason-phrase validation

These changes preserve existing byte semantics while making signedness handling explicit and portable.

Acceptance matrix

Adds docs/release/v1.0-acceptance.md, mapping frozen functional/non-functional requirement groups to concrete test, CI, benchmark, package, and documentation evidence.

Roadmap

Marks v0.9 complete and v1.0 release hardening as in progress. The project version intentionally remains 0.9.0; the 1.0.0 bump is deferred until all automated gates and manual acceptance checks are green.

Scope

No new HTTP behavior, networking feature, public API semantic, or product-scope change is introduced by this PR. Source edits discovered by warnings-as-errors are release-hardening portability fixes only.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Make the Clang warnings-as-errors gate buildable

With the Ubuntu/Clang configuration used by this job, enabling CPP_REQUEST_WARNINGS_AS_ERRORS makes the new gate fail during compilation before any sanitizer tests run: Clang reports -Wsign-conversion for the character loops in src/core/url.cpp:42 and src/http/request_serializer.cpp:93,134,143. I reproduced this using the workflow's configuration with Clang 17; fix these warnings or avoid promoting them to errors here so the required release gate can become green.

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