Add Conan package manager support

[Copilot]

Adds a Conan recipe (conanfile.py) so libhv can be consumed via the Conan package manager.

• conanfile.py — Recipe exposing all CMake build options as Conan options (with_openssl, with_http, with_mqtt, with_evpp, with_kcp, enable_uds, etc.). Handles optional dependencies (openssl, nghttp2, mbedtls) and platform-specific system libs. Correctly maps static library name (hv_static) vs shared (hv).
• test_package/ — Standard Conan test package that links against libhv and calls hv_version() to validate the built package.

Usage

# Local build & test
conan create . libhv/1.3.4@ -o libhv:with_openssl=True

# Consume in a project's conanfile.txt
[requires]
libhv/1.3.4

Original prompt

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This section details on the original issue you should resolve

<issue_title>什么时候libhv上传到conan包管理器里？</issue_title>
<issue_description>什么时候libhv上传到conan包管理器里？</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes 什么时候libhv上传到conan包管理器里？ #491

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