fix(ostool): harden local U-Boot TFTP staging lifecycle

[YanLien]

Summary

Fix local U-Boot network configuration handling and make Linux TFTP staging shorter, safer, and automatically cleaned after each run.

Changes

• Make the TOML [net] section work directly with LocalBackend, including settings such as interface and tftp_dir.
• Replace the full artifact directory hierarchy with a shorter generated TFTP path:

  ostool/<pid>-<timestamp>-<counter>/<fit-image>
  

• Track and remove staged FIT images after the U-Boot run.
• Roll back the staging directory when copying the FIT image fails.
• Reject unsafe TFTP roots, parent segments, fabricated paths, and symlinked namespace directories.
• Ensure console cleanup, TFTP cleanup, and board power-off handling still run when an earlier operation fails.
• Preserve the original run error when additional cleanup errors occur.
• Document the user-group permissions required to clean /srv/tftp/ostool without sudo rmdir.

Compatibility

The existing TOML format remains unchanged:

[net]
interface = "eth0"

Remote board execution is unaffected because its network configuration continues to come from the server boot profile.

[mai-team-app]

本 PR 将 Linux 系统 tftpd-hpa 的 FIT 暂存改为受限的 ostool/<唯一目录> 命名空间，并在本地 U-Boot 运行收尾阶段清理文件和目录；同时把网络配置归入本地配置结构，并补充了中英文权限配置说明。改动影响本地 Linux 的 U-Boot/TFTP 启动与清理路径；远程开发板上传路径保持独立，未发现共享 API 或配置契约回归。

审查结论：暂存路径验证、冲突处理、失败回滚及清理错误聚合均有针对性测试覆盖；未发现未解决问题或额外测试缺口。未发现既有审查意见或讨论需要跟进；相似 PR 搜索未发现重叠项。

验证：GitHub Actions check (stable, x86_64-unknown-linux-gnu) 已成功（包含 CI 的格式化、clippy、构建和测试流程）。本地已通过 git diff --check 并复核目标 HEAD；本地环境未安装 cargo，因此无法在此环境重跑 cargo fmt --check、cargo clippy --manifest-path ostool/Cargo.toml --all-features -- -D warnings 和 cargo test --manifest-path ostool/Cargo.toml --all-features。CI 无由本 PR 引起的失败。

Powered by gpt-5.6-terra