chore: 移除 Windows arm64 构建与发布支持

Windows ARM64 使用场景极少，windows-11-arm runner 上 MSYS2
CLANGARM64 交叉编译不稳定，CGO 编译问题难以排查，维护成本
远超收益。移除 arm64 的 CI 矩阵条目、Makefile Windows 变量、
versionctl 资产白名单、README 文档和规范中的相关需求。
Linux 和 macOS arm64 不受影响。

.github/workflows/release.yml

@@ -161,15 +161,6 @@ jobs:
             packages: >-
               make
               mingw-w64-x86_64-gcc
-          - arch: arm64
-            runner: windows-11-arm
-            msystem: CLANGARM64
-            cc: clang
-            cxx: clang++
-            packages: >-
-              make
-              mingw-w64-clang-aarch64-clang
-              mingw-w64-clang-aarch64-llvm
     permissions:
       contents: read
     steps:
@@ -214,17 +205,8 @@ jobs:
           "$CC" --version
           command -v "$CXX"
           "$CXX" --version
-          if [ "${{ matrix.arch }}" = "arm64" ]; then
-            if command -v llvm-windres >/dev/null 2>&1; then
-              llvm-windres --version
-            else
-              command -v windres
-              windres --version
-            fi
-          else
-            command -v windres
-            windres --version
-          fi
+          command -v windres
+          windres --version
           if command -v powershell.exe >/dev/null 2>&1; then
             powershell.exe -NoProfile -Command '$PSVersionTable.PSVersion.ToString()'
           else