Add KlingAiping usage-token settlement from upstream final_unit_deduction and duration fallback handling.

Normalize model endpoint config persistence and convert model pricing values between stored USD and display currency in the editor.

Co-Authored-By: Codex <noreply@anthropic.com>

- 避免仅编辑展示价格时写入默认真实计费规则
- 将 video-extend 纳入 KlingAiping 原生渠道约束
- 补充相关保存决策、渠道约束和计费展示测试

Co-Authored-By: Codex <noreply@anthropic.com>

- 新增 KlingAiping 渠道 (ChannelTypeKlingAiping = 59)
- 新增 KlingAiping 原生路由 (text2video/image2video/omni-video 等)
- 新增 KlingAiping adaptor (relay/channel/task/kling/aiping/)
- 前端模型定价页面新增「真实计费 / 展示价格」Tab 切换
- 新增 DisplayPricing 组件，支持模型展示价格的增删改
- 新增 displayPricingConfig 工具函数及测试
- 修复 KlingAiping 路由路径匹配与 task 错误响应

Co-Authored-By: Claude <noreply@anthropic.com>