add initial project structure with configuration, models, and API key authentication

internal/database/database.go

@@ -0,0 +1,23 @@
+package database
+
+import (
+	"time"
+
+	_ "github.com/go-sql-driver/mysql"
+	"github.com/jmoiron/sqlx"
+
+	"emly-api-go/internal/config"
+)
+
+func Connect(cfg *config.Config) (*sqlx.DB, error) {
+	db, err := sqlx.Connect("mysql", cfg.DSN)
+	if err != nil {
+		return nil, err
+	}
+
+	db.SetMaxOpenConns(25)
+	db.SetMaxIdleConns(5)
+	db.SetConnMaxLifetime(5 * time.Minute)
+
+	return db, nil
+}