fix(ci): Flutter 归档解压加 --no-same-owner，并登记 safe.directory

run 8 实测：1.58GB 归档 3 分钟下完、解压成功，最后卡在
  fatal: detected dubious ownership in repository at '/root/development/flutter'
flutter 工具链启动时会调 git 取版本，被该保护拦下 → exit 128。
根因是归档内 uid 非 0，root 身份解压仍按原 uid 设属主。
解压加 --no-same-owner，并额外 git config --global safe.directory 兜底。

.gitea/workflows/design-system-guard.yml

@@ -82,10 +82,16 @@ jobs:
           mkdir -p "$HOME/development"
           echo "下载 $URL"
           curl -fsSL --retry 3 --retry-delay 5 --connect-timeout 20 -o /tmp/flutter.tar.xz "$URL"
-          tar xf /tmp/flutter.tar.xz -C "$HOME/development"
+          # --no-same-owner：归档内的 uid 不是 0，按原 uid 解压会让
+          # /root/development/flutter 属主≠root，git 2.35+ 随即报
+          # "fatal: detected dubious ownership"，而 flutter 工具链启动时
+          # 会调用 git 取版本 → 直接 exit 128。run 8 就死在这里。
+          tar --no-same-owner -xf /tmp/flutter.tar.xz -C "$HOME/development"
           rm -f /tmp/flutter.tar.xz
           echo "$HOME/development/flutter/bin" >> "$GITHUB_PATH"
           echo "FLUTTER_BIN=$HOME/development/flutter/bin/flutter" >> "$GITHUB_ENV"
+          # 双保险：即便属主仍有偏差，也让 git 认这个目录。
+          git config --global --add safe.directory "$HOME/development/flutter"
           "$HOME/development/flutter/bin/flutter" --version
 
       - name: Run design system guards