feat: 添加组合模型支持和OmniRoute集成

[sabason]

feat(provider): 扩展Provider类型以支持组合模型配置
feat(proxy): 添加组合模型解析和路由逻辑
feat(api): 在模型列表中返回组合模型信息
feat(i18n): 添加修正Base URL的翻译文本
feat(test): 添加连接测试的备用URL回退机制
feat(ui): 在设置页面显示修正的Base URL建议
chore: 添加开发构建脚本和批处理文件

[github-actions]

PR quality triage

Changed areas: none

CLI core policy: No CLI-core policy block detected.

CLI core files:

• none

Expected checks:

• change-policy

Test coverage signals:

• No obvious missing-test signal from changed paths.

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