Fix postinst: Install sensorpajen package in venv

The venv had dependencies installed but not the sensorpajen package itself,
causing 'No module named sensorpajen' errors when running.

Changes:
- After installing dependencies from requirements.txt
- Now also runs 'pip install --no-deps .' to install sensorpajen
- Uses --no-deps to avoid re-installing already-installed dependencies
- Installed in /opt/sensorpajen where pyproject.toml exists

Fixes: ModuleNotFoundError: No module named 'sensorpajen'

debian/postinst

@@ -48,7 +48,7 @@ case "$1" in
             venv/bin/pip install -r /opt/sensorpajen/requirements.txt
         else
             echo "Warning: requirements.txt not found, installing bluepy and paho-mqtt directly"
-            venv/bin/pip install bluepy paho-mqtt
+            venv/bin/pip install bluepy paho-mqtt pybluez
         fi
         
         if [ $? -ne 0 ]; then
@@ -56,6 +56,15 @@ case "$1" in
             exit 1
         fi
 
+        # Install sensorpajen package itself
+        echo "Installing sensorpajen application..."
+        cd /opt/sensorpajen
+        venv/bin/pip install --no-deps . || {
+            echo "Error: Failed to install sensorpajen package"
+            exit 1
+        }
+        cd /
+
         # Set ownership of application directory BEFORE setting capabilities
         chown -R sensorpajen:sensorpajen /opt/sensorpajen