[diffusion][llm] macOS support (#19549)

Signed-off-by: Xiaodong Ye <yeahdongcn@gmail.com>
Co-authored-by: Mick <mickjagger19@icloud.com>

docs/platforms/apple_metal.md

@@ -0,0 +1,20 @@
+# Apple Silicon with Metal
+
+This document describes how run SGLang on Apple Silicon using [Metal](https://developer.apple.com/metal/). If you encounter issues or have questions, please [open an issue](https://github.com/sgl-project/sglang/issues).
+
+## Install SGLang
+
+You can install SGLang using one of the methods below.
+
+### Install from Source
+
+```bash
+# Use the default branch
+git clone https://github.com/sgl-project/sglang.git
+cd sglang
+
+# Install sglang python package
+pip install --upgrade pip
+rm -f python/pyproject.toml && mv python/pyproject_other.toml python/pyproject.toml
+uv pip install -e "python[all_mps]"
+```