fix(protocol): preserve VLESS HTTP upgrade URI options

[cesaryuan]

描述

修复 VLESS URI 编码未保留 HTTP Upgrade 扩展的问题，确保 Mihomo 节点经过“配置 → URI → 配置”往返转换后仍使用原有传输方式。

关联 Issue

Fixes #262

更改类型

• 🐛 修复 Bug (Bug)
• ✨ 新功能 (Feature)
• 📝 文档更新 (Docs)
• 🎨 样式或界面改进 (UI)
• ♻️ 代码重构 (Refactor)
• ⚡ 性能优化 (Perf)
• 🔧 配置更改 (Config)
• 🧪 测试更新 (Test)

更改内容

• 当 HttpUpgrade 启用时，在 VLESS URI 中写入 httpUpgrade=1
• 当 HttpUpgradeFastOpen 启用时，在 VLESS URI 中写入 httpUpgradeFastOpen=1
• 扩展现有 VLESS 编解码测试，验证两个字段均可无损往返

截图

不适用。

检查清单

• 我的代码遵循项目代码风格

• 后端检查已通过

  golangci-lint run
  go test ./...
  

• 前端改动已运行 yarn run lint

• UI 改动已检查 light/dark 和响应式状态

• 已按需补充或更新后端测试、注释和文档

• 行为或契约变化时，已检查跨层同步

• 本次更改不会引入安全漏洞

已运行命令或检查：

gofmt -l <all Go files>                                  # 通过，无输出
go run github.com/golangci/golangci-lint/v2/cmd/golangci-lint@v2.12.2 run  # 通过，0 issues
go test ./node/protocol -run TestVlessEncodeDecode -count=1                # 通过
go test <all packages except sublink/api>                                  # 通过
go test ./...                                                               # node/protocol 通过；Windows 下既有 api 测试失败

本地全量测试的 api 失败与本改动无关：部分测试将 Windows t.TempDir() 返回的反斜杠路径直接拼入 JSON，随后返回“配置读取错误”。PR 的 Linux GitHub Actions 将继续执行仓库规定的完整 go test ./...。

其他说明

这是编码器层面的最小修复。URI 解码、Mihomo 导入和 Mihomo 输出路径已经支持这两个字段，无需修改 API、前端、配置或文档。

[Copilot]

Pull request overview

This pull request fixes VLESS URI encoding so that Mihomo nodes retain the v2ray-http-upgrade and v2ray-http-upgrade-fast-open transport semantics after a “config → URI → config” roundtrip, preventing unintended downgrade back to plain WebSocket.

Changes:

• Update EncodeVLESSURL to emit httpUpgrade=1 when Query.HttpUpgrade == 1.
• Update EncodeVLESSURL to emit httpUpgradeFastOpen=1 when Query.HttpUpgradeFastOpen == 1.
• Extend the VLESS encode/decode roundtrip test to assert both fields are preserved.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
node/protocol/vless.go	Adds encoding of httpUpgrade and httpUpgradeFastOpen query parameters when enabled to preserve HTTP Upgrade transport options.
node/protocol/vless_test.go	Extends the roundtrip test to cover HttpUpgrade and HttpUpgradeFastOpen so regressions are caught.

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