Enhance AI and Redis integration for smoke logging features

- Added AI configuration options to .env.example and config.go for OpenAI integration.
- Implemented Redis caching for session management in main.go and auth middleware.
- Updated smoke logging service to support real smoking time (`smoke_at`) and AI advice retrieval.
- Enhanced API routes to include endpoints for AI advice and unlock functionality for non-members.
- Improved database schema with new tables for AI advice and unlock records.
- Expanded documentation to cover new AI features and Redis caching implementation.

internal/routes/smoke_routes.go

@@ -15,5 +15,9 @@ func registerSmokeRoutes(protected *gin.RouterGroup, smokeHandler *smokehandler.
 		smoke.GET("/logs/:id", smokeHandler.Get)
 		smoke.PUT("/logs/:id", smokeHandler.Update)
 		smoke.DELETE("/logs/:id", smokeHandler.Delete)
+
+		// AI 戒烟建议（会员优先；非会员需看广告解锁）
+		smoke.GET("/ai/advice", smokeHandler.GetAIAdvice)
+		smoke.POST("/ai/advice_unlocks", smokeHandler.UnlockAIAdvice)
 	}
 }