Fix compatibility issues with Qt/PyQt6 versions

- Add null check for message.message in search filter
- Handle missing colorScheme/colorSchemeChanged methods for older Qt versions
- Add display check to prevent hanging in headless environments
- Update build documentation with system package alternative
- Update PyInstaller spec for Python 3.12
- Improve run.sh script with venv management

BUILDING.md

@@ -7,6 +7,16 @@ $ pip install -r requirements.txt
 $ pip install pyinstaller
 ```
 
+**Alternative: System packages (Debian/Ubuntu)**
+
+If you prefer to use system packages instead of pip, install the required PyQt6 packages:
+
+```shell
+$ apt install python3-pyqt6 python3-pyqt6.qtwebsockets python3-pyqt6.qtmultimedia
+```
+
+Note: This may require specific Python versions and may not include the latest features.
+
 Currently it's only possible to create installer packages from the pyinstaller output. For any target platform, first create the executable with pyinstaller:
 
 ```shell