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

run.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+
+# Check if virtual environment exists
+if [ ! -d "venv" ]; then
+    echo "Creating virtual environment..."
+    python3 -m venv venv
+    echo "Installing dependencies..."
+    source venv/bin/activate
+    pip install -r requirements.txt
+else
+    source venv/bin/activate
+fi
+
+# Run the application
+python -m gotify_tray