feat: Eino nodes 迁移到 trace 包（Phase 6.2）

- nodes_stt.go 使用 trace.FromContext 替换 logger.Log
- nodes_history.go 使用 trace.FromContext
- nodes_tts.go 使用 trace.FromContext
- nodes_done.go 使用 trace.FromContext
- 移除所有 nodes 中的 request_id 手动字段（自动附加）
- 所有日志消息改为英文

backend/internal/eino/nodes_history.go

@@ -8,9 +8,9 @@ import (
 	"github.com/cloudwego/eino/schema"
 
 	"github.com/hhs/camtalk/internal/ai/llm"
-	"github.com/hhs/camtalk/internal/logger"
 	"github.com/hhs/camtalk/internal/models"
 	"github.com/hhs/camtalk/internal/store"
+	"github.com/hhs/camtalk/internal/trace"
 )
 
 // NewHistoryLambda 创建历史组装 Lambda 节点。
@@ -24,7 +24,7 @@ func NewHistoryLambda(
 	maxHistory int,
 ) *compose.Lambda {
 	return compose.InvokableLambda(func(ctx context.Context, sttOut STTOutput) ([]*schema.Message, error) {
-		log := logger.Log
+		log := trace.FromContext(ctx)
 
 		// 从 State 读取请求元数据
 		state := stateFromCtx(ctx)
@@ -48,7 +48,7 @@ func NewHistoryLambda(
 		if userID != "" && scenarioRepo != nil {
 			scenarios, err := scenarioRepo.FindByUserID(ctx, userID)
 			if err != nil {
-				log.Warnw("加载用户自建情景失败", "user_id", userID, "error", err)
+				log.Warnw("load user scenarios failed", "user_id", userID, "error", err)
 			} else if len(scenarios) > 0 {
 				customScenarios = make(map[string]string, len(scenarios))
 				customGreetings = make(map[string]string, len(scenarios))
@@ -58,7 +58,7 @@ func NewHistoryLambda(
 						customGreetings[s.ID] = s.Greeting
 					}
 				}
-				log.Debugw("加载用户自建情景", "user_id", userID, "count", len(scenarios))
+				log.Debugw("loaded user scenarios", "user_id", userID, "count", len(scenarios))
 			}
 		}
 
@@ -78,7 +78,7 @@ func NewHistoryLambda(
 		if historyFetcher != nil && sessionID != "" {
 			history, err := historyFetcher(ctx, sessionID, maxHistory)
 			if err != nil {
-				log.Warnw("获取历史消息失败，继续处理", "error", err, "request_id", requestID)
+				log.Warnw("fetch history failed, continuing", "error", err, "request_id", requestID)
 			} else {
 				for _, msg := range history {
 					messages = append(messages, &schema.Message{
@@ -121,8 +121,7 @@ func NewHistoryLambda(
 			})
 		}
 
-		log.Infow("历史组装完成",
-			"request_id", requestID,
+		log.Infow("history assembled",
 			"message_count", len(messages),
 			"has_image", len(imageData) > 0,
 			"scenario", scenario)