refactor(update scripts): enhance directory handling and error management

- Updated update-backend.sh and update-frontend.sh to accept a target directory as a parameter, improving flexibility.
- Refactored paths to use the target directory for all operations, ensuring consistency and reducing hardcoded values.
- Added error handling with 'set -euo pipefail' for better script reliability.
- Improved user feedback by displaying the target directory during updates.

update.sh

@@ -1,7 +1,10 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
+TARGET_DIR="${1:?Zielverzeichnis fehlt: ./update.sh <z. B. /opt/yourpart-green>}"
+
 echo "=== YourPart Update Script ==="
+echo "Ziel-Slot: $TARGET_DIR"
 echo "Aktualisiert die Anwendung, ohne .env-Dateien zu überschreiben"
 echo ""
 
@@ -35,11 +38,11 @@ fi
 
 echo ""
 echo "=== Updating Backend ==="
-./update-backend.sh
+./update-backend.sh "$TARGET_DIR"
 
 echo ""
 echo "=== Building and Updating Frontend ==="
-./update-frontend.sh
+./update-frontend.sh "$TARGET_DIR"
 
 echo ""
 echo "=== Update Completed! ==="