feat(database): add repairSmokeAIAdviceIndexes function and corresponding tests

- Implemented repairSmokeAIAdviceIndexes to manage the unique index for fa_smoke_ai_advice.
- Added unit tests for the new function to ensure correct index recreation and validation.
- Updated AutoMigrate to include the new index repair function.

internal/smoke/service/smoke_ai_next_smoke_service.go

@@ -154,7 +154,7 @@ func (s *SmokeAINextSmokeService) GetOrGenerate(ctx context.Context, user *userm
 	}
 	inputJSON, _ := json.Marshal(input)
 
-	output, outputJSON, modelName, tokensIn, tokensOut, err := s.callAI(ctx, input)
+	output, outputJSON, modelName, tokensIn, tokensOut, err := s.callAI(ctx, int(user.ID), input)
 	if err != nil {
 		return AINextSmokeSuggestion{}, err
 	}
@@ -249,6 +249,14 @@ func (s *SmokeAINextSmokeService) GetOrGenerate(ctx context.Context, user *userm
 	if err != nil {
 		return AINextSmokeSuggestion{}, err
 	}
+	if len(nodes) > 0 {
+		if firstNodeAt, err := parseFlexibleTime(nodes[0], planDate); err == nil {
+			suggestedAt = firstNodeAt.In(time.Local)
+			if suggestedAt.Before(notBeforeAt) {
+				suggestedAt = notBeforeAt
+			}
+		}
+	}
 
 	if cachedAdvice != nil {
 		if err := s.db.WithContext(ctx).
@@ -612,7 +620,9 @@ func (s *SmokeAINextSmokeService) saveNodes(ctx context.Context, uid int, planDa
 	return nil
 }
 
-func (s *SmokeAINextSmokeService) callAI(ctx context.Context, input aiNextSmokeInput) (aiNextSmokeOutput, []byte, string, *int, *int, error) {
+func (s *SmokeAINextSmokeService) callAI(ctx context.Context, uid int, input aiNextSmokeInput) (aiNextSmokeOutput, []byte, string, *int, *int, error) {
+	requestModel := preferredSmokeAIModel(s.cfg.Model)
+
 	systemPrompt := strings.TrimSpace(`
 你是一名专业的戒烟教练与行为改变顾问。你将收到一段 JSON，包含：
 - 现在时间(as_of)
@@ -638,9 +648,16 @@ func (s *SmokeAINextSmokeService) callAI(ctx context.Context, input aiNextSmokeI
 `)
 
 	userPrompt := fmt.Sprintf("输入(JSON)：\n%s", mustJSON(input))
+	appendSmokeAIDebugLog("next_smoke.request", map[string]interface{}{
+		"uid":           uid,
+		"model":         requestModel,
+		"system_prompt": systemPrompt,
+		"user_prompt":   userPrompt,
+		"input":         input,
+	})
 
 	reqBody := chatCompletionRequest{
-		Model: s.cfg.Model,
+		Model: requestModel,
 		Messages: []chatMessage{
 			{Role: "system", Content: systemPrompt},
 			{Role: "user", Content: userPrompt},
@@ -671,6 +688,12 @@ func (s *SmokeAINextSmokeService) callAI(ctx context.Context, input aiNextSmokeI
 	if err != nil {
 		return aiNextSmokeOutput{}, nil, "", nil, nil, fmt.Errorf("read ai response: %w", err)
 	}
+	appendSmokeAIDebugLog("next_smoke.response", map[string]interface{}{
+		"uid":           uid,
+		"model":         requestModel,
+		"http_status":   resp.StatusCode,
+		"response_body": string(body),
+	})
 	if resp.StatusCode != http.StatusOK {
 		return aiNextSmokeOutput{}, nil, "", nil, nil, fmt.Errorf("ai http %d: %s", resp.StatusCode, truncateString(string(body), 512))
 	}
@@ -700,7 +723,7 @@ func (s *SmokeAINextSmokeService) callAI(ctx context.Context, input aiNextSmokeI
 
 	modelName := parsed.Model
 	if modelName == "" {
-		modelName = s.cfg.Model
+		modelName = requestModel
 	}
 
 	var tokensIn, tokensOut *int