Introduced new unit tests for DataProcessing to validate SmlValueProcessor behavior. Updated SmlValueProcessor to track GridPowerBalance and use a customizable TimeProvider. Made minor refactors and included new test project setup in the solution file.

Previously, the script deleted the contents of the installation directory directly. Now, it renames the existing installation directory to a backup location before proceeding, ensuring no files are lost until the new installation is confirmed successful.

Removed the redundant ContentType setting when publishing MQTT messages for cleaner code. Updated SmlValueProcessor to ignore zero values and removed unnecessary complete action in the subscription. Adjusted package versions in the project file to match the correct dependencies.

Added a new async method to handle MQTT client reconnection on disconnection. Modified message publishing to support both JSON and string payloads with a new `WriteAsJson` flag in `SmartMeterValue`. Updated MQTTnet package version and refactored server stop procedures for better code organization.

Corrected the sign inversion logic for grid power balance calculation in SmlValueProcessor. The update ensures that current purchasing power and current selling power values are processed with the correct sign. This resolves issues with interpreting power flow direction.