fix(archive): prefer utf-8 for non-EFS zip names

[Lanfei]

Summary / 摘要

This PR fixes garbled filenames when previewing ZIP archives whose entries do not set the EFS flag.

Previously, OpenList always decoded non-EFS ZIP entry names with non_efs_zip_encoding (default: IBM437). In practice, some ZIP tools store filenames as valid UTF-8 but do not set the EFS flag, which caused Chinese and other non-ASCII filenames to appear garbled.

Changes in this PR:

• Prefer the original filename when the ZIP entry has the EFS flag.
• For non-EFS ZIP entries, return the original name first if it is already valid UTF-8.
• Only fall back to non_efs_zip_encoding when the raw filename is not valid UTF-8.
• Add unit tests covering:
  • valid UTF-8 names without EFS
  • fallback decoding with configured encoding
  • unchanged behavior when EFS is set

User-visible behavior:

• ZIP preview now displays more non-EFS UTF-8 filenames correctly.
• Legacy non-UTF-8 ZIP files still use the configured fallback encoding.

Compatibility:

• No breaking changes.

• No public API, config schema, storage format, or migration behavior changes.

• This PR has breaking changes.
  / 此 PR 包含破坏性变更。

• This PR changes public API, config, storage format, or migration behavior.
  / 此 PR 修改了公开 API、配置、存储格式或迁移行为。

• This PR requires corresponding changes in related repositories.
  / 此 PR 需要关联仓库同步修改。

Related repository PRs / 关联仓库 PR:

• OpenList-Frontend:
• OpenList-Docs:

Testing / 测试

• go test ./...
• Manual test / 手动测试:
  • go test ./internal/archive/zip
  • Verified the updated decoding logic with unit tests for UTF-8-first fallback behavior.

Checklist / 检查清单

• I have read CONTRIBUTING.
  / 我已阅读 CONTRIBUTING。
• I confirm this contribution follows the repository license, contribution policy, and code of conduct.
  / 我确认此贡献符合仓库许可证、贡献规范和行为准则。
• I have formatted the changed code with gofmt, go fmt, or prettier where applicable.
  / 我已按适用情况使用 gofmt、go fmt 或 prettier 格式化变更代码。
• I have requested review from relevant maintainers or code owners where applicable.
  / 我已在适用情况下请求相关维护者或代码所有者审查。

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• This PR includes AI-assisted content.
  / 此 PR 包含 AI 辅助内容。

Tools used / 使用工具:

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Usage scope / 使用范围:

• Code generation / 代码生成

• Refactoring / 重构

• Documentation / 文档

• Tests / 测试

• Translation / 翻译

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  / 我已审核并验证此 PR 中的所有 AI 辅助内容。

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