Fix: Close existing SQL connections before backup to prevent abnormal termination

- Added explicit connection cleanup in createDatabaseBackup()
- Resolves 'BACKUP DATABASE is terminating abnormally' error in runBackupProcess()
- Prevents connection pool conflicts when running scheduled backups

index.js

@@ -144,13 +144,21 @@ async function getDbSizeBytes() {
 async function createDatabaseBackup() {
   try {
     console.log('Connecting to database...');
+    
+    // Close any existing connection to avoid conflicts
+    try {
+      await sql.close();
+    } catch (closeErr) {
+      // Ignore error if no connection exists
+    }
+    
     await sql.connect(config);
 
     console.log('Creating database backup...');
     const backupQuery = `
       BACKUP DATABASE [${process.env.MSSQL_DATABASE}] 
       TO DISK = N'${backupFilePath}' 
-      WITH FORMAT, INIT, NAME = N'${process.env.MSSQL_DATABASE}-Vollständig Datenbank Sichern', 
+      WITH FORMAT, INIT, COMPRESSION, NAME = N'${process.env.MSSQL_DATABASE}-Vollständig Datenbank Sichern', 
       SKIP, NOREWIND, NOUNLOAD, STATS = 10
     `;