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/common/redis/service/client.go

@@ -0,0 +1,58 @@
+package service
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/redis/go-redis/v9"
+
+	"wx_service/config"
+)
+
+type Client struct {
+	rc         *redis.Client
+	keyPrefix  string
+	sessionTTL time.Duration
+}
+
+func NewClient(cfg config.RedisConfig) (*Client, error) {
+	if cfg.Addr == "" {
+		return nil, nil
+	}
+
+	rc := redis.NewClient(&redis.Options{
+		Addr:     cfg.Addr,
+		Password: cfg.Password,
+		DB:       cfg.DB,
+	})
+
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+	if err := rc.Ping(ctx).Err(); err != nil {
+		return nil, fmt.Errorf("ping redis: %w", err)
+	}
+
+	ttlSeconds := cfg.SessionTTLSeconds
+	if ttlSeconds <= 0 {
+		ttlSeconds = 86400
+	}
+
+	return &Client{
+		rc:         rc,
+		keyPrefix:  cfg.KeyPrefix,
+		sessionTTL: time.Duration(ttlSeconds) * time.Second,
+	}, nil
+}
+
+func (c *Client) Redis() *redis.Client {
+	return c.rc
+}
+
+func (c *Client) KeyPrefix() string {
+	return c.keyPrefix
+}
+
+func (c *Client) SessionTTL() time.Duration {
+	return c.sessionTTL
+}