Add HTTP gzip/zstd compression and WebSocket permessage-deflate support

[ProjectSky]

• Add configurable HTTP gzip/zstd compression support
• Add WebSocket permessage-deflate negotiation & message handling
• Add WITH_ZLIB/WITH_ZSTD build options and update build/docs/CI
• Add compression-related unit tests

[Copilot]

Pull request overview

This PR adds first-class HTTP response/request compression (gzip/zstd) and WebSocket permessage-deflate support, including negotiation, framing (RSV1), and extensive unit test coverage. It also introduces new build toggles (WITH_ZLIB/WITH_ZSTD) and wires them into the project’s build + CI tooling.

Changes:

• Add HTTP compression utilities (Accept-Encoding selection, request/response compression, streaming decompression) and integrate into HTTP server/client paths.
• Add WebSocket permessage-deflate negotiation plus RSV1-aware frame building, compression on send, and decompression in the WebSocket parser.
• Add new HTTP/WebSocket compression unit tests and update CMake/Make/Bazel/CI/build docs to support zlib/zstd options.

Reviewed changes

Copilot reviewed 40 out of 40 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
unittest/websocket_compression_test.cpp	Adds negotiation + parser safety tests and an end-to-end compressed WebSocket echo test.
unittest/http_compression_test.cpp	Adds comprehensive HTTP compression/decompression behavior tests (client/server, headers, edge cases).
unittest/CMakeLists.txt	Builds the new compression test binaries under HTTP-enabled configurations.
scripts/unittest.sh	Runs new compression tests when the binaries are present.
http/wsdef.h / http/wsdef.c	Adds ws_build_frame_ex to support RSV1 when building frames.
http/websocket_parser.h / http/websocket_parser.c	Tracks RSV bits during parse and supports RSV1 emission during build.
http/server/WebSocketServer.h	Adds server-side WebSocket compression options to WebSocketService.
http/server/HttpService.h	Adds server-wide HttpCompressionOptions defaults on HttpService.
http/server/HttpResponseWriter.h / .cpp	Threads request/service context into writer and applies compression before sending headers/body.
http/server/HttpHandler.h / .cpp	Implements request decompression, response compression, static-file ETag variance by encoding, and WS extension negotiation.
http/http_compress.h / http/http_compress.cpp	Introduces the shared compression implementation (HTTP + WS helpers, streaming decoder, deflater/inflater).
http/client/WebSocketClient.h / .cpp	Adds permessage-deflate offer/confirm logic and config surface to the client.
http/client/HttpClient.h / .cpp	Adds client compression configuration, request auto-compress, response auto-decode via adapter; adjusts redirect flow.
http/client/AsyncHttpClient.h / .cpp	Adds response decoder adapter support and request auto-compress for async client.
http/WebSocketParser.h / .cpp	Adds permessage-deflate decompression support and stricter frame validation (RSV/opcodes/control frames).
http/WebSocketChannel.h / .cpp	Adds permessage-deflate compression on send and RSV1 marking on first frame.
http/HttpMessage.h / .cpp	Adds compression options to messages plus Content-Encoding helpers and Accept-Encoding builder.
http/HttpCompression.h	Defines public compression option structs and content-encoding enums.
configure / config.ini	Adds configure/config toggles for WITH_ZLIB/WITH_ZSTD.
cmake/vars.cmake / CMakeLists.txt	Adds headers and build options for zlib/zstd.
Makefile.vars / Makefile.in / Makefile	Adds headers and link flags, and builds compression tests in make unittest.
BUILD.md	Documents how to build with zlib/zstd enabled.
BUILD.bazel	Adds zlib/zstd defines/linkopts and new compression cc_test targets.
.github/workflows/CI.yml	Installs zlib/zstd deps and enables them in CI configure invocation.
base/herr.h	Adds new error codes for unsupported encoding/compress/decompress failures.

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