在 Yi.Framework.AiHub.Domain.Shared/Dtos/Anthropic/AnthropicChatCompletionDto.cs 中新增字段: - AnthropicChatCompletionDto: Signature、StopSequence(带 JsonPropertyName) - AnthropicChatCompletionDtoContentBlock: signature(小写字段) - AnthropicCompletionDtoUsage: CacheCreation、ServiceTier(带 JsonPropertyName)