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_model.go

@@ -0,0 +1,13 @@
+package service
+
+import "strings"
+
+// preferredSmokeAIModel 避免把高延迟 reasoning 模型用于首页/计划类交互接口。
+func preferredSmokeAIModel(model string) string {
+	normalized := strings.TrimSpace(model)
+	lower := strings.ToLower(normalized)
+	if strings.Contains(lower, "deepseek") && strings.Contains(lower, "reasoner") {
+		return "deepseek-chat"
+	}
+	return normalized
+}