Refactor and remove sqlite and replace with MySQL

internal/helpers/security/admin.go

@@ -0,0 +1,16 @@
+package security
+
+import (
+	"database/sql"
+	"log"
+)
+
+func IsAdmin(db *sql.DB, userID int) bool {
+	var isAdmin bool
+	err := db.QueryRow(`SELECT is_admin FROM users WHERE id = ?`, userID).Scan(&isAdmin)
+	if err != nil {
+		log.Printf("⚠️ Failed to check is_admin for user %d: %v", userID, err)
+		return false
+	}
+	return isAdmin
+}