docs(packaging): 记录 Termux glibc 构建与 termux-x11 运行配方

新增 packaging/docs/termux-glibc-build.md：glibc 工具链（Rust gnu 组件 +
patchelf + clang/lld + Debian libgcc crt）、构建环境（LD_PRELOAD/CA/USTC 镜像）、
termux-x11 运行与截图取证、GPU 现状与已知边界。
支持矩阵四处同步：Termux 行从「GUI 未验证」改为「源码自建、CPU 渲染单机验证过」，
仍标注实验级、不在发布矩阵内。

packaging/release-notes.md

@@ -59,7 +59,7 @@ Published = shipped as a download of **this** release, listed in `SHA256SUMS.txt
 | Linux arm64, X11 | not built (unverified) | first class (unverified) | glibc 2.35+, `libxkbcommon`, `fontconfig`, `libGL`, `libxcb` |
 | Linux arm64, Wayland | not built (unverified) | supported (unverified) | the above plus `wayland-client` |
 | Windows 8.1/8/7 | not built | unsupported | the baseline is Windows 10 |
-| Android — Termux + X11 | not built (no CI slot) | experimental, not promised | CLI only and only when built from source; GUI unverified |
+| Android — Termux + X11 | not built (no CI slot) | experimental, not promised | CLI and GUI from source only; GUI verified once on CPU rendering (see `packaging/docs/termux-glibc-build.md`) |
 
 `windows-x64` is the only published slot this release; Windows ARM64 is kept out until its build is green
 (see Downloads above). Both arm64 rows are formal matrix slots, not the experimental Termux path, and