feat: distill 支持 reasoning 模型 + LLM_ENDPOINT 配置

- engine.go: 解析 LLM 响应时 content 为空则用 reasoning_content
- engine.go: Message 结构体加 ReasoningContent 字段
- service: LLM_ENDPOINT/LLM_MODEL/LLM_API_KEY 环境变量
- 模型: glm-4.7-flash (localhost:3000 v1 proxy)

go/internal/distill/engine.go

@@ -256,7 +256,8 @@ func (e *Engine) callLLM5D(content string) (FiveDScore, error) {
 	var result struct {
 		Choices []struct {
 			Message struct {
-				Content string `json:"content"`
+				Content          string `json:"content"`
+				ReasoningContent string `json:"reasoning_content"`
 			} `json:"message"`
 		} `json:"choices"`
 	}
@@ -270,7 +271,11 @@ func (e *Engine) callLLM5D(content string) (FiveDScore, error) {
 	}
 
 	var score FiveDScore
-	json.Unmarshal([]byte(result.Choices[0].Message.Content), &score)
+	llmContent := result.Choices[0].Message.Content
+	if llmContent == "" {
+		llmContent = result.Choices[0].Message.ReasoningContent
+	}
+	json.Unmarshal([]byte(llmContent), &score)
 	return score, nil
 }