test(storage): build invalid UTF-8 path with Git plumbing

[M4n5ter]

English

Summary

• construct the invalid UTF-8 Git path fixture with Git plumbing instead of the host filesystem
• preserve the original 0xff path byte through the repository tree
• keep the public managed-workspace validation path unchanged

Why

The previous fixture asked macOS to create a filename containing an invalid UTF-8 byte. APFS rejects that setup with EILSEQ before the managed-workspace code runs, making the test platform-dependent and preventing it from exercising the intended boundary.

The new fixture writes the blob, tree, and commit directly through Git plumbing, then marks the path skip-worktree so Git does not materialize it. The product code still reads the raw ls-tree -z bytes and rejects the non-UTF-8 source tree.

Closes #2095.

Validation

• focused regression test
• full @maka/storage test suite: 634 passed, 12 skipped, 0 failed
• npm run typecheck -w @maka/storage
• npm run build -w @maka/storage
• npm run lint
• Biome format check
• git diff --check

中文

概要

• 使用 Git plumbing 构造非法 UTF-8 路径测试夹具，不再依赖宿主文件系统创建该路径
• 在 Git tree 中原样保留 0xff 路径字节
• 保持公开的 managed-workspace 校验路径不变

原因

旧测试要求 macOS 文件系统创建包含非法 UTF-8 字节的文件名。APFS 会在 managed-workspace 代码运行前以 EILSEQ 拒绝该操作，导致测试依赖平台，也无法覆盖原本要验证的产品边界。

新测试通过 Git plumbing 直接写入 blob、tree 和 commit，再将该路径标记为 skip-worktree，避免 Git 将其物化到文件系统。产品代码仍通过 ls-tree -z 读取原始路径字节，并拒绝非 UTF-8 source tree。

Closes #2095.

验证

• 定向回归测试
• 完整 @maka/storage 测试：634 passed，12 skipped，0 failed
• npm run typecheck -w @maka/storage
• npm run build -w @maka/storage
• npm run lint
• Biome format check
• git diff --check