[Upstream] feat: add AGIone channel

[Sagit-chu]

Synced from upstream PR: songquanpeng#2407

我已确认该 PR 已自测通过。该改动主要是后端渠道适配和渠道配置项，不涉及产品 UI 流程；验证截图为终端测试结果。

测试命令：

go test ./relay/adaptor/openai ./relay/channeltype
go test ./relay/... ./controller -run 'TestNonExistent'
git diff --check origin/main..HEAD
gitleaks detect --no-git --redact --verbose --source /tmp/one-api-agione.diff

测试结果摘要：

ok  github.com/songquanpeng/one-api/relay/adaptor/openai
ok  github.com/songquanpeng/one-api/relay/channeltype
git diff --check: ok
no leaks found

本 PR 新增 AGIone 渠道支持：

• 渠道类型：AGIone / 52
• 默认地址：https://agione.pro/hyperone/xapi/api/v1
• 适配方式：复用 OpenAI-compatible adaptor
• 模型示例：openai/GPT-5.5/c6fbe、anthropic/Claude-opus-4.7/a4d5d、deepseek/deepseek-v4-pro/d3462

同时补了 AGIone URL 拼接测试，避免默认 base URL 已带 /v1 时把请求拼成 /v1/v1/chat/completions。

Submitted by the AGIone team.