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.

.env.example

@@ -17,6 +17,16 @@ SHORT_VIDEO_API_KEY=replace-with-real-key
 SHORT_VIDEO_FREE_QUOTA=20
 SHORT_VIDEO_TIMEOUT_SECONDS=5
 
+# AI 配置（OpenAI-compatible）
+# 例：OpenAI = https://api.openai.com/v1
+AI_BASE_URL=https://api.openai.com/v1
+AI_API_KEY=replace-with-ai-api-key
+AI_MODEL=gpt-4o-mini
+AI_TIMEOUT_SECONDS=15
+
+# 简易后台接口鉴权（用于生成兑换码等）
+ADMIN_API_TOKEN=replace-with-strong-random-token
+
 # 七牛直传配置（Kodo）
 QINIU_ACCESS_KEY=replace-with-access-key
 QINIU_SECRET_KEY=replace-with-secret-key
@@ -34,3 +44,11 @@ QINIU_TOKEN_EXPIRE_SECONDS=300
 WECHAT_OA_APP_ID=replace-with-oa-appid
 WECHAT_OA_APP_SECRET=replace-with-oa-appsecret
 WECHAT_OA_TIMEOUT_SECONDS=5
+
+# Redis（可选，用于缓存 session_key -> user）
+# 不配置 REDIS_ADDR 时，程序会自动禁用 Redis，保持原来每次请求查 MySQL 的方式。
+REDIS_ADDR=127.0.0.1:6379
+REDIS_PASSWORD=
+REDIS_DB=0
+REDIS_KEY_PREFIX=wx_service:
+REDIS_SESSION_TTL_SECONDS=86400