feat(release): M51 —— 发布矩阵补 Linux arm64 与 Windows arm64 两槽位（六槽位）

- release.yml：加 linux-arm64（原生 ubuntu-24.04-arm runner）与 windows-arm64
  （windows-latest 上交叉编译到 aarch64-pc-windows-msvc）；产物根改由
  matrix.build_dir 参数化，dumpbin 自检与打包都吃矩阵路径而非硬编码 target/release；
  交叉槽位多两步（rustup target add + ARM64 库体检），release job 的槽位齐全性
  检查从四扩到六。
- make_artifacts.py：--slot / --build-dir 参数化 + 六槽位映射；打包前回读可执行文件头
  （PE 机器码 / ELF e_machine / Mach-O cputype）校验架构，跨槽位构建自动跳过
  ull --version 冒烟并打印原因（不在 x64 上假装跑得动 arm64 二进制）。
- packaging/README.md + release-notes.md：两张支持矩阵同步加 Windows 11 ARM64 与
  Linux arm64 行；arm64 glibc 地板如实写 2.39（高于 x64 的 2.35），并说明与 Termux
  实验级的区别（这两个是正式发布槽位）。

本地验证：宿主判定注入（七个组合 + 非法宿主 exit 1）、文件头架构识别（真 x64 exe +
合成 PE/ELF/Mach-O 头）、windows-arm64 stub 全流程、架构守卫真拦、linux-arm64 归档
两次 sha256 一致、windows-x64 原生回归（冒烟 + sha256sum -c）。arm64 真机构建由 CI 补。

packaging/release-notes.md

@@ -9,7 +9,9 @@ No WebView, no bundled runtime, no JRE download needed to start the launcher its
 | Platform | Asset | Notes |
 | --- | --- | --- |
 | Windows 10/11 x64 | `unlucky-launcher-{{VERSION}}-windows-x64.exe` | single exe, double-click to run |
+| Windows 11 ARM64 | `unlucky-launcher-{{VERSION}}-windows-arm64.exe` | single exe, runs natively on ARM64 Windows |
 | Linux x64 (X11/Wayland) | `unlucky-launcher-{{VERSION}}-linux-x64.tar.gz` | single binary inside, no installer |
+| Linux arm64 (X11/Wayland) | `unlucky-launcher-{{VERSION}}-linux-arm64.tar.gz` | single binary inside; needs glibc 2.39+ |
 | macOS 12+ Apple Silicon | `unlucky-launcher-{{VERSION}}-macos-arm64.tar.gz` | single binary inside, no installer |
 | macOS 12+ Intel | `unlucky-launcher-{{VERSION}}-macos-x64.tar.gz` | single binary inside, no installer |
 
@@ -22,22 +24,30 @@ with the download on every platform.
 | Platform | Level | Runtime requirements |
 | --- | --- | --- |
 | Windows 10/11 x64 | first class | nothing beyond the OS (UCRT is part of Win10+) |
+| Windows 11 ARM64 | first class (launcher artifact) | nothing extra; launcher runs natively, the game itself runs through the OS x64 emulation layer with an x64 JDK |
 | macOS 12+ (arm64 / x64) | first class | nothing; unsigned build, see Gatekeeper note |
 | Linux x64, X11 | first class | `libxkbcommon`, `fontconfig`, `libGL` (or software renderer), `libxcb` |
 | Linux x64, Wayland | supported | `wayland-client`, `libxkbcommon`, plus the X11 set for XWayland apps |
+| Linux arm64, X11 | first class | glibc **2.39+** (built on `ubuntu-24.04-arm`, higher than the x64 floor of 2.35), `libxkbcommon`, `fontconfig`, `libGL`, `libxcb` |
+| Linux arm64, Wayland | supported | the above plus `wayland-client` |
 | Windows 8.1/8/7 | unsupported | baseline was raised to Win10 (decision D21) |
 | Android — Termux + X11 | experimental, not promised | CLI only (build from source), GUI unverified; not part of this release matrix |
 
+Both arm64 rows are **formally released slots** (the assets ship in this release and in
+`SHA256SUMS.txt`), not the experimental Termux path: Linux arm64 is built and smoke-tested on a
+native ARM64 runner, Windows ARM64 is cross-built with the same static-CRT gate as x64.
+
 ## Install
 
-**Windows** — put the `.exe` anywhere and run it. Portable data lives next to the exe when a
+**Windows** — put the `.exe` anywhere and run it (pick `-windows-arm64.exe` on ARM64 Windows,
+`-windows-x64.exe` everywhere else). Portable data lives next to the exe when a
 `portable.marker` file is present, otherwise under `%APPDATA%`.
 
 **Linux**
 
 ```bash
-tar -xzf unlucky-launcher-{{VERSION}}-linux-x64.tar.gz
-cd unlucky-launcher-{{VERSION}}-linux-x64
+tar -xzf unlucky-launcher-{{VERSION}}-linux-x64.tar.gz   # use linux-arm64 on aarch64
+cd unlucky-launcher-{{VERSION}}-linux-x64                # ditto
 chmod +x unlucky-launcher && ./unlucky-launcher
 ```