llama.cpp b9849 release: IPv6 URL handling and new binaries

The llama.cpp b9849 release introduces support for bracketed IPv6 literals in URL authorities, allowing the server to parse [host]:port forms per RFC 3986. This update ensures proper formatting of listening logs, proxy headers, and client rebuilds while maintaining bare remote_addr for per-request tracking.

• The URL parser now handles bracketed IPv6 hosts and restores explicit rejection for unsupported schemes.
• macOS builds include Apple Silicon (arm64) and Intel (x64) binaries, alongside an iOS XCFramework.
• Linux distributions provide CPU, Vulkan, ROCm 7.2, OpenVINO, and SYCL variants for x64, arm64, and s390x architectures.
• Windows releases feature CPU, CUDA 12/13, Vulkan, OpenVINO, SYCL, and HIP backends for x64 and arm64.
• Android arm64 (CPU) binaries are available, along with a general UI package.

This release enables users to deploy llama.cpp servers in environments requiring strict IPv6 compliance while providing updated binaries across major operating systems and hardware accelerators.