b11048

metal : support qwen4exp hc ops (#29000)

Add support for the new DSV4 HC op variants used by qwen4exp:

• hc_pre with per-element sigmoid gate (gated variant)
• hc_post with identity mixing (comb == nullptr)

Assisted-by: pi:llama.cpp/Qwen3.8-27B

Website:

• https://llama.app

Attestations:

• https://github.com/ggml-org/llama.cpp/attestations/48621858

macOS/iOS:

• macOS Apple Silicon (arm64)
• macOS Apple Silicon (arm64, KleidiAI enabled) DISABLED
• macOS Intel (x64)
• iOS XCFramework

Linux:

• Ubuntu x64 (CPU)
• Ubuntu arm64 (CPU)
• Ubuntu s390x (CPU)
• Ubuntu x64 (Vulkan)
• Ubuntu arm64 (Vulkan)
• Ubuntu x64 (CUDA 12) - CUDA 12.8 libraries
• Ubuntu x64 (CUDA 13) - CUDA 13.3 libraries
• Ubuntu arm64 (CUDA 13) - CUDA 13.3 libraries
• Ubuntu x64 (ROCm 10.0)
• Ubuntu x64 (OpenVINO)
• Ubuntu x64 (SYCL FP32)
• Ubuntu x64 (SYCL FP16)

Android:

• Android arm64 (CPU)

Windows:

• Windows x64 (CPU)
• Windows arm64 (CPU)
• Windows arm64 (OpenCL Adreno)
• Windows x64 (CUDA 12) - CUDA 12.4 DLLs
• Windows x64 (CUDA 13) - CUDA 13.4 DLLs
• Windows arm64 (CUDA 13) - CUDA 13.4 DLLs
• Windows x64 (Vulkan)
• Windows x64 (OpenVINO)
• Windows x64 (SYCL)
• Windows x64 (ROCm 10.0)

openEuler:

• DISABLED
• openEuler x86 (310p)
• openEuler x86 (910b, ACL Graph)
• openEuler aarch64 (310p)
• openEuler aarch64 (910b, ACL Graph)

• UI