readme: surface download link and CI badge at top

Makes the prebuilt download discoverable without having to read to the
"Downloading a prebuilt xcframework" section:

- Shields.io badge showing the latest release tag
- CI status badge for the fork workflow
- Plain-text direct download link with a SHA256 companion link

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: apocryphx

README.md

@@ -1,7 +1,12 @@
 # llama.cpp — Apple Platforms Fork
 
+[![Download llama.xcframework.zip](https://img.shields.io/github/v/release/apocryphx/llama.cpp?include_prereleases&label=llama.xcframework&sort=date)](https://github.com/apocryphx/llama.cpp/releases/latest)
+[![CI](https://github.com/apocryphx/llama.cpp/actions/workflows/fork-xcframework-release.yml/badge.svg)](https://github.com/apocryphx/llama.cpp/actions/workflows/fork-xcframework-release.yml)
+
 A fork of [ggml-org/llama.cpp](https://github.com/ggml-org/llama.cpp) focused on producing a working `llama.xcframework` for local on-device inference across all current Apple platforms.
 
+**→ [Download the latest prebuilt `llama.xcframework.zip`](https://github.com/apocryphx/llama.cpp/releases/download/latest/llama.xcframework.zip)** ([sha256](https://github.com/apocryphx/llama.cpp/releases/download/latest/llama.xcframework.zip.sha256)) — rebuilt on every push to `master` and weekly.
+
 The goal of this fork is narrow: keep a shippable xcframework building on a modern macOS toolchain (Xcode 26+, CMake 4.x). No feature additions, no diverging APIs — everything else is pulled straight from upstream.
 
 ## What this fork changes