feat(payment): 优化支付配置与 Anthropic 兼容处理

[PIXEL-AI-API]

• 新增支付配置字段在后台设置接口、DTO 和前端管理页中的读写支持
• 调整支付页展示逻辑和类型定义，完善用户侧支付入口表现
• 优化 Anthropic 到 Responses 的转换，补充相关兼容测试
• 修正账单服务和支付配置服务的边界行为，并补充单元测试
• 将后端版本号更新到 1.0.27

验证：

• go test -C backend ./internal/handler ./internal/service ./internal/pkg/apicompat
• pnpm --dir frontend exec vitest run src/views/admin/tests/SettingsView.spec.ts src/views/user/tests/PaymentView.spec.ts

[github-actions]

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I have read the CLA Document and I hereby sign the CLA

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1 out of 2 committers have signed the CLA.
✅ (AzurCrystal)[https://github.com/AzurCrystal]
❌ @Open-Pixel-AI
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[AzurCrystal]

Close Due to Out of Date