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.

go.mod

@@ -5,6 +5,7 @@ go 1.23.6
 require (
 	github.com/gin-gonic/gin v1.11.0
 	github.com/joho/godotenv v1.5.1
+	github.com/redis/go-redis/v9 v9.17.2
 	gorm.io/driver/mysql v1.6.0
 	gorm.io/gorm v1.31.1
 )
@@ -13,7 +14,9 @@ require (
 	filippo.io/edwards25519 v1.1.0 // indirect
 	github.com/bytedance/sonic v1.14.0 // indirect
 	github.com/bytedance/sonic/loader v0.3.0 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/cloudwego/base64x v0.1.6 // indirect
+	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
 	github.com/gabriel-vasile/mimetype v1.4.8 // indirect
 	github.com/gin-contrib/sse v1.1.0 // indirect
 	github.com/go-playground/locales v0.14.1 // indirect