增加数据库配置：默认 sqlite3、支持 mysql，启动时连接校验

internal/store/store.go

@@ -0,0 +1,50 @@
+package store
+
+import (
+	"database/sql"
+	"fmt"
+	"time"
+
+	_ "github.com/go-sql-driver/mysql"
+	_ "modernc.org/sqlite"
+
+	"myaibot/internal/config"
+)
+
+func Open(cfg *config.DatabaseConfig) (*sql.DB, error) {
+	driver, dsn, err := resolve(cfg)
+	if err != nil {
+		return nil, err
+	}
+	db, err := sql.Open(driver, dsn)
+	if err != nil {
+		return nil, fmt.Errorf("打开数据库失败: %w", err)
+	}
+	db.SetMaxOpenConns(10)
+	db.SetMaxIdleConns(5)
+	db.SetConnMaxLifetime(30 * time.Minute)
+	if err := db.Ping(); err != nil {
+		db.Close()
+		return nil, fmt.Errorf("数据库连接失败: %w", err)
+	}
+	return db, nil
+}
+
+func Close(db *sql.DB) {
+	if db != nil {
+		db.Close()
+	}
+}
+
+func resolve(cfg *config.DatabaseConfig) (driver, dsn string, err error) {
+	switch cfg.Driver {
+	case "sqlite3":
+		return "sqlite", cfg.File, nil
+	case "mysql":
+		dsn := fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?charset=utf8mb4&parseTime=True&loc=Local",
+			cfg.User, cfg.Password, cfg.Host, cfg.Port, cfg.Name)
+		return "mysql", dsn, nil
+	default:
+		return "", "", fmt.Errorf("不支持的数据库驱动: %s", cfg.Driver)
+	}
+}