feat(group): 增加messages调度模型映射配置

backend/internal/domain/openai_messages_dispatch.go

@@ -0,0 +1,10 @@
+package domain
+
+// OpenAIMessagesDispatchModelConfig controls how Anthropic /v1/messages
+// requests are mapped onto OpenAI/Codex models.
+type OpenAIMessagesDispatchModelConfig struct {
+	OpusMappedModel    string            `json:"opus_mapped_model,omitempty"`
+	SonnetMappedModel  string            `json:"sonnet_mapped_model,omitempty"`
+	HaikuMappedModel   string            `json:"haiku_mapped_model,omitempty"`
+	ExactModelMappings map[string]string `json:"exact_model_mappings,omitempty"`
+}